Exhibit 8

List of Subsidiaries

As at 31 March 2013



|    |  |                                                                                                                   |  |                                  
|--- |  | ----------------------------------------------------------------------------------------------------------------- |  | ---------------------------------
|    |  | Name                                                                                                              |  | Country of
Incorporation         
|1.  |  | 65 WILLIS LANE, INC.                                                                                              |  | USA                              
|2.  |  | ASSETHALL LIMITED                                                                                                 |  | England & Wales                  
|3.  |  | BEEGAS NOMINEES LIMITED                                                                                           |  | England & Wales                  
|4.  |  | BIRCH SITES LIMITED                                                                                               |  | England & Wales                  
|5.  |  | BLACKWATER A LIMITED                                                                                              |  | England & Wales                  
|6.  |  | BLACKWATER B LIMITED                                                                                              |  | England & Wales                  
|7.  |  | BLACKWATER C LIMITED                                                                                              |  | England & Wales                  
|8.  |  | BLACKWATER D LIMITED                                                                                              |  | England & Wales                  
|9.  |  | BLACKWATER E LIMITED                                                                                              |  | England & Wales                  
|10. |  | BLACKWATER H LIMITED                                                                                              |  | England & Wales                  
|11. |  | BLACKWATER J LIMITED                                                                                              |  | England & Wales                  
|12. |  | BOSTON GAS COMPANY (incl Essex Gas Company)                                                                       |  | USA                              
|13. |  | BRITISH TRANSCO CAPITAL INC                                                                                       |  | USA                              
|14. |  | BRITISH TRANSCO FINANCE (NO 1) LIMITED                                                                            |  | Cayman Islands                   
|15. |  | BRITISH TRANSCO FINANCE (NO 2) LIMITED                                                                            |  | Cayman Islands                   
|16. |  | BRITISH TRANSCO FINANCE (NO 3) LIMITED                                                                            |  | England & Wales                  
|17. |  | BRITISH TRANSCO FINANCE (NO 5) LIMITED                                                                            |  | England & Wales                  
|18. |  | BRITISH TRANSCO FINANCE INC                                                                                       |  | USA                              
|19. |  | BRITISH TRANSCO INTERNATIONAL FINANCE BV                                                                          |  | The Netherlands                  
|20. |  | BRITNED DEVELOPMENT LIMITED (50%)                                                                                 |  | England & Wales                  
|21. |  | BROKEN BRIDGE CORP.                                                                                               |  | USA                              
|22. |  | CLEAN LINE ENERGY PARTNERS LLC (approximately 15%
holding)                                                        |  | USA                              
|23. |  | COLONIAL GAS COMPANY                                                                                              |  | USA                              
|24. |  | CONNECTICUT YANKEE ATOMIC POWER COMPANY
(19.5%)                                                                   |  | USA                              
|25. |  | CORESO SA (22.485%%)                                                                                              |  | Belgium                          
|26. |  | DIRECT GLOBAL POWER, INC. (26%)                                                                                   |  | USA                              
|27. |  | ELEXON LIMITED                                                                                                    |  | England & Wales                  
|28. |  | ENERGIS PLC (33.06%)                                                                                              |  | England & Wales                  
|29. |  | EUA ENERGY INVESTMENT CORPORATION                                                                                 |  | USA                              
|30. |  | EUA FRC II ENERGY ASSOCIATES                                                                                      |  | USA                              
|31. |  | EVIONYX, INC. (16%)                                                                                               |  | USA                              
|32. |  | GRIDAMERICA HOLDINGS INC                                                                                          |  | USA                              
|33. |  | GRIDCOM LIMITED                                                                                                   |  | England & Wales                  
|34. |  | GREENERU INC (17%)                                                                                                |  | USA                              
|35. |  | INVERSIONES ABC LTDA (98.84%)                                                                                     |  | Chile                            
|36. |  | IROQUOIS GAS TRANSMISSION SYSTEM, L.P.
(20.4%)                                                                    |  | USA                              
|37. |  | IROQUOIS PIPELINE OPERATING COMPANY (effectively 20.4% via
Iroquois Gas Transmission System, L.P. 100% ownership) |  | USA                              
|38. |  | ISLAND ENERGY SERVICES COMPANY, INC.                                                                              |  | USA                              
|39. |  | ISLANDER EAST PIPELINE COMPANY, LLC (50%)                                                                         |  | USA                              
|40. |  | JOINT RADIO COMPANY LIMITED (50%)                                                                                 |  | England & Wales                  
|41. |  | JV NOMINEES 2012 LIMITED                                                                                          |  | England & Wales                  
|42. |  | KEYSPAN (U.K.)                                                                                                    |  | England & Wales                  
|43. |  | KEYSPAN C.I. II, LTD                                                                                              |  | Cayman Islands                   
|44. |  | KEYSPAN C.I., LTD                                                                                                 |  | Cayman Islands                   
|45. |  | KEYSPAN CI MIDSTREAM LIMITED                                                                                      |  | USA                              
|46. |  | KEYSPAN CORPORATION                                                                                               |  | USA                              
|47. |  | KEYSPAN ENERGY CORPORATION                                                                                        |  | USA                              
|48. |  | KEYSPAN ENERGY DEVELOPMENT CO.                                                                                    |  | Canadian (Providence Nova Scotia)
|49. |  | KEYSPAN ENERGY SERVICES INC.                                                                                      |  | USA                              
|50. |  | KEYSPAN GAS EAST CORPORATION                                                                                      |  | USA                              
|51. |  | KEYSPAN INTERNATIONAL CORPORATION                                                                                 |  | USA                              
|52. |  | KEYSPAN MHK, INC.                                                                                                 |  | USA                              
|53. |  | KEYSPAN MIDSTREAM INC.                                                                                            |  | USA                              
|54. |  | KEYSPAN PLUMBING SOLUTIONS, INC.                                                                                  |  | USA                              
|55. |  | KSI CONTRACTING, LLC                                                                                              |  | USA                              
|56. |  | KSI ELECTRICAL, LLC                                                                                               |  | USA                              



---

Exhibit 8

List of Subsidiaries

As at 31 March 2013



|     |  |                                                  |  |                         
|---- |  | ------------------------------------------------ |  | ------------------------
|     |  | Name                                             |  | Country of Incorporation
|57.  |  | KSI MECHANICAL, LLC                              |  | USA                     
|58.  |  | LAND MANAGEMENT AND DEVELOPMENT, INC             |  | USA                     
|59.  |  | LANDRANCH LIMITED                                |  | England & Wales         
|60.  |  | LANDWEST, INC                                    |  | USA                     
|61.  |  | LATTICE ENERGY SERVICES LIMITED                  |  | England & Wales         
|62.  |  | LATTICE GROUP EMPLOYEE BENEFIT TRUST LIMITED     |  | England & Wales         
|63.  |  | LATTICE GROUP INTERNATIONAL HOLDINGS LIMITED     |  | England & Wales         
|64.  |  | LATTICE GROUP PLC                                |  | England & Wales         
|65.  |  | LATTICE GROUP TRUSTEES LIMITED                   |  | England & Wales         
|66.  |  | LATTICE OPSCO LIMITED                            |  | England & Wales         
|67.  |  | LATTICE TELECOM FINANCE (NO 1) LIMITED           |  | Isle of Man             
|68.  |  | MAINE YANKEE ATOMIC POWER COMPANY (24%)          |  | USA                     
|69.  |  | MAINSTREAM FORTY-SEVEN LIMITED                   |  | England & Wales         
|70.  |  | MASSACHUSETTS ELECTRIC COMPANY                   |  | USA                     
|71.  |  | MELMAR LIMITED                                   |  | Isle of Man             
|72.  |  | METRO ENERGY, L.L.C.                             |  | USA                     
|73.  |  | METROWEST REALTY LLC                             |  | USA                     
|74.  |  | MILLENNIUM PIPELINE COMPANY, LLC (26.25%)        |  | USA                     
|75.  |  | MYHOMEGATE, INC.                                 |  | USA                     
|76.  |  | MYHOMEKEY.COM, INC. (18.2%)                      |  | USA                     
|77.  |  | MYSTIC STEAMSHIP CORPORATION                     |  | USA                     
|78.  |  | NANTUCKET ELECTRIC COMPANY                       |  | USA                     
|79.  |  | NATGRID FINANCE HOLDINGS LIMITED                 |  | England & Wales         
|80.  |  | NATGRID FINANCE LIMITED                          |  | England & Wales         
|81.  |  | NATGRID INVESTMENTS LIMITED                      |  | England & Wales         
|82.  |  | NATGRID LIMITED                                  |  | England & Wales         
|83.  |  | NATGRID ONE LIMITED                              |  | England & Wales         
|84.  |  | NATGRIDTW1 LIMITED                               |  | England & Wales         
|85.  |  | NATIONAL GRID (IOM) UK LTD                       |  | Isle of Man             
|86.  |  | NATIONAL GRID (IRELAND) 1 LIMITED                |  | Republic of Ireland     
|87.  |  | NATIONAL GRID (IRELAND) 2 LIMITED                |  | Republic of Ireland     
|88.  |  | NATIONAL GRID (SOUTHALL) GENERAL PARTNER LIMITED |  | England & Wales         
|89.  |  | NATIONAL GRID (SOUTHALL) LP LIMITED              |  | England & Wales         
|90.  |  | NATIONAL GRID (US) HOLDINGS LIMITED              |  | England & Wales         
|91.  |  | NATIONAL GRID (US) INVESTMENTS                   |  | England & Wales         
|92.  |  | NATIONAL GRID (US) INVESTMENTS 2 LIMITED         |  | England & Wales         
|93.  |  | NATIONAL GRID (US) INVESTMENTS 3                 |  | England & Wales         
|94.  |  | NATIONAL GRID (US) INVESTMENTS 4 LIMITED         |  | England & Wales         
|95.  |  | NATIONAL GRID (US) PARTNER 1 LIMITED             |  | England & Wales         
|96.  |  | NATIONAL GRID (US) PARTNER 2 LIMITED             |  | England & Wales         
|97.  |  | NATIONAL GRID AUSTRALIA PTY LIMITED              |  | Australia               
|98.  |  | NATIONAL GRID BELGIUM LIMITED                    |  | England & Wales         
|99.  |  | NATIONAL GRID BLUE POWER FINANCE LIMITED         |  | England & Wales         
|100. |  | NATIONAL GRID BLUE POWER LIMITED                 |  | England & Wales         
|101. |  | NATIONAL GRID BRAZIL B.V.                        |  | The Netherlands         
|102. |  | NATIONAL GRID BRAZIL FINANCE                     |  | England & Wales         
|103. |  | NATIONAL GRID CARBON LIMITED                     |  | England & Wales         
|104. |  | NATIONAL GRID CHILE B.V.                         |  | The Netherlands         
|105. |  | NATIONAL GRID COMMERCIAL HOLDINGS LIMITED        |  | England & Wales         
|106. |  | NATIONAL GRID DEVELOPMENT HOLDINGS CORP.         |  | USA                     
|107. |  | NATIONAL GRID EIGHT                              |  | England & Wales         
|108. |  | NATIONAL GRID EIGHTEEN LIMITED                   |  | England & Wales         
|109. |  | NATIONAL GRID ELECTRIC SERVICES LLC              |  | USA                     
|110. |  | NATIONAL GRID ELECTRICITY GROUP TRUSTEE LIMITED  |  | England & Wales         
|111. |  | NATIONAL GRID ELECTRICITY TRANSMISSION PLC       |  | England & Wales         
|112. |  | NATIONAL GRID ELEVEN                             |  | England & Wales         



---

Exhibit 8

List of Subsidiaries

As at 31 March 2013



|     |  |                                                       |  |                         
|---- |  | ----------------------------------------------------- |  | ------------------------
|     |  | Name                                                  |  | Country of Incorporation
|113. |  | NATIONAL GRID ENERGY MANAGEMENT, LLC                  |  | USA                     
|114. |  | NATIONAL GRID ENERGY SERVICES, LLC                    |  | USA                     
|115. |  | NATIONAL GRID ENERGY TRADING SERVICES LLC             |  | USA                     
|116. |  | NATIONAL GRID ENGINEERING & SURVEY INC.               |  | USA                     
|117. |  | NATIONAL GRID FIFTEEN LIMITED                         |  | England & Wales         
|118. |  | NATIONAL GRID FINANCE B.V.                            |  | The Netherlands         
|119. |  | NATIONAL GRID FIVE LIMITED                            |  | England & Wales         
|120. |  | NATIONAL GRID FOUR LIMITED                            |  | England & Wales         
|121. |  | NATIONAL GRID FOURTEEN LIMITED                        |  | England & Wales         
|122. |  | NATIONAL GRID GAS FINANCE (NO 1) PLC                  |  | England & Wales         
|123. |  | NATIONAL GRID GAS HOLDINGS LIMITED                    |  | England & Wales         
|124. |  | NATIONAL GRID GAS PLC                                 |  | England & Wales         
|125. |  | NATIONAL GRID GENERATION LLC                          |  | USA                     
|126. |  | NATIONAL GRID GLENWOOD ENERGY CENTER, LLC             |  | USA                     
|127. |  | NATIONAL GRID GOLD LIMITED                            |  | England & Wales         
|128. |  | NATIONAL GRID GRAIN LNG LIMITED                       |  | England & Wales         
|129. |  | NATIONAL GRID HOLDINGS B.V.                           |  | The Netherlands         
|130. |  | NATIONAL GRID HOLDINGS LIMITED                        |  | England & Wales         
|131. |  | NATIONAL GRID HOLDINGS ONE PLC                        |  | England & Wales         
|132. |  | NATIONAL GRID IGTS CORP.                              |  | USA                     
|133. |  | NATIONAL GRID INDIA B.V.                              |  | The Netherlands         
|134. |  | NATIONAL GRID INDUS B.V.                              |  | The Netherlands         
|135. |  | NATIONAL GRID INSURANCE COMPANY (IRELAND) LIMITED     |  | Republic of Ireland     
|136. |  | NATIONAL GRID INSURANCE COMPANY (ISLE OF MAN)
LIMITED |  | Isle of Man             
|137. |  | NATIONAL GRID INTERCONNECTOR HOLDINGS LIMITED         |  | England & Wales         
|138. |  | NATIONAL GRID INTERCONNECTORS LIMITED                 |  | England & Wales         
|139. |  | NATIONAL GRID INTERNATIONAL LIMITED                   |  | England & Wales         
|140. |  | NATIONAL GRID ISLANDER EAST PIPELINE LLC              |  | USA                     
|141. |  | NATIONAL GRID JERSEY HOLDINGS FIVE LIMITED            |  | Jersey                  
|142. |  | NATIONAL GRID JERSEY INVESTMENTS LIMITED              |  | Jersey                  
|143. |  | NATIONAL GRID LAND AND PROPERTIES LIMITED             |  | England & Wales         
|144. |  | NATIONAL GRID LAND DEVELOPMENTS LIMITED               |  | England & Wales         
|145. |  | NATIONAL GRID LAND INVESTMENTS LIMITED                |  | England & Wales         
|146. |  | NATIONAL GRID LNG GP LLC                              |  | USA                     
|147. |  | NATIONAL GRID LNG LP                                  |  | USA                     
|148. |  | NATIONAL GRID LNG LP LLC                              |  | USA                     
|149. |  | NATIONAL GRID MANQUEHUE B.V.                          |  | The Netherlands         
|150. |  | NATIONAL GRID METERING LIMITED                        |  | England & Wales         
|151. |  | NATIONAL GRID MIDDLE EAST FZCO                        |  | United Arab Emirates    
|152. |  | NATIONAL GRID MILLENNIUM LLC                          |  | USA                     
|153. |  | NATIONAL GRID NE HOLDINGS 2 LLC                       |  | USA                     
|154. |  | NATIONAL GRID NEMO LINK LIMITED                       |  | England & Wales         
|155. |  | NATIONAL GRID NETHERLANDS ONE BV                      |  | The Netherlands         
|156. |  | NATIONAL GRID NETHERLANDS THREE BV                    |  | The Netherlands         
|157. |  | NATIONAL GRID NETHERLANDS TWO BV                      |  | The Netherlands         
|158. |  | NATIONAL GRID NINE LIMITED                            |  | England & Wales         
|159. |  | NATIONAL GRID NINETEEN LIMITED                        |  | England & Wales         
|160. |  | NATIONAL GRID NORTH AMERICA INC                       |  | USA                     
|161. |  | NATIONAL GRID NORTH EAST VENTURES INC                 |  | USA                     
|162. |  | NATIONAL GRID NSN LINK LIMITED                        |  | England & Wales         
|163. |  | NATIONAL GRID OFFSHORE LTD                            |  | England & Wales         
|164. |  | NATIONAL GRID ONE LIMITED                             |  | England & Wales         
|165. |  | NATIONAL GRID OVERSEAS LIMITED                        |  | England & Wales         
|166. |  | NATIONAL GRID OVERSEAS TWO LIMITED                    |  | England & Wales         
|167. |  | NATIONAL GRID PLC                                     |  | England & Wales         
|168. |  | NATIONAL GRID POLAND B.V.                             |  | The Netherlands         



---

Exhibit 8

List of Subsidiaries

As at 31 March 2013



|     |  |                                                                 |  |                         
|---- |  | --------------------------------------------------------------- |  | ------------------------
|     |  | Name                                                            |  | Country of Incorporation
|169. |  | NATIONAL GRID PORT JEFFERSON ENERGY CENTER, LLC                 |  | USA                     
|170. |  | NATIONAL GRID PROCUREMENT BV                                    |  | The Netherlands         
|171. |  | NATIONAL GRID PROPERTY (HIGH WYCOMBE) LIMITED                   |  | England & Wales         
|172. |  | NATIONAL GRID PROPERTY (NORTHAMPTON) LIMITED                    |  | England & Wales         
|173. |  | NATIONAL GRID PROPERTY (NORTHFLEET) LIMITED                     |  | England & Wales         
|174. |  | NATIONAL GRID PROPERTY (TAUNTON) LIMITED                        |  | England & Wales         
|175. |  | NATIONAL GRID PROPERTY (WARWICK) LIMITED                        |  | England & Wales         
|176. |  | NATIONAL GRID PROPERTY DEVELOPMENTS LIMITED                     |  | England & Wales         
|177. |  | NATIONAL GRID PROPERTY HOLDINGS LIMITED                         |  | England & Wales         
|178. |  | NATIONAL GRID PROPERTY LIMITED                                  |  | England & Wales         
|179. |  | NATIONAL GRID SERVICES, INC.                                    |  | USA                     
|180. |  | NATIONAL GRID SEVEN LIMITED                                     |  | England & Wales         
|181. |  | NATIONAL GRID SEVENTEEN LIMITED                                 |  | England & Wales         
|182. |  | NATIONAL GRID SIX LIMITED                                       |  | England & Wales         
|183. |  | NATIONAL GRID SIXTEEN LIMITED                                   |  | England & Wales         
|184. |  | NATIONAL GRID TECHNOLOGIES INC.                                 |  | USA                     
|185. |  | NATIONAL GRID TEN                                               |  | England & Wales         
|186. |  | NATIONAL GRID THIRTY LIMITED                                    |  | England & Wales         
|187. |  | NATIONAL GRID THREE LIMITED                                     |  | England & Wales         
|188. |  | NATIONAL GRID TRANSMISSION SERVICES CORPORATION                 |  | USA                     
|189. |  | NATIONAL GRID TWELVE LIMITED                                    |  | England & Wales         
|190. |  | NATIONAL GRID TWENTY EIGHT LIMITED                              |  | England & Wales         
|191. |  | NATIONAL GRID TWENTY FOUR LIMITED                               |  | England & Wales         
|192. |  | NATIONAL GRID TWENTY LIMITED                                    |  | England & Wales         
|193. |  | NATIONAL GRID TWENTY NINE LIMITED                               |  | England & Wales         
|194. |  | NATIONAL GRID TWENTY ONE LIMITED                                |  | England & Wales         
|195. |  | NATIONAL GRID TWENTY SEVEN LIMITED                              |  | England & Wales         
|196. |  | NATIONAL GRID TWENTY THREE LIMITED                              |  | England & Wales         
|197. |  | NATIONAL GRID TWENTY-FIVE LIMITED                               |  | England & Wales         
|198. |  | NATIONAL GRID TWENTY-SIX LIMITED                                |  | England & Wales         
|199. |  | NATIONAL GRID TWO LIMITED                                       |  | England & Wales         
|200. |  | NATIONAL GRID UK LIMITED                                        |  | England & Wales         
|201. |  | NATIONAL GRID UK PENSION SERVICES LIMITED                       |  | England & Wales         
|202. |  | NATIONAL GRID US 6 LLC                                          |  | USA                     
|203. |  | NATIONAL GRID US 7 INC.                                         |  | USA                     
|204. |  | NATIONAL GRID US LLC                                            |  | USA                     
|205. |  | NATIONAL GRID USA                                               |  | USA                     
|206. |  | NATIONAL GRID USA SERVICE COMPANY, INC.                         |  | USA                     
|207. |  | NATIONAL GRID ZAMBIA LIMITED                                    |  | England & Wales         
|208. |  | NEES ENERGY, INC.                                               |  | USA                     
|209. |  | NEW ENGLAND ELECTRIC TRANSMISSION CORPORATION                   |  | USA                     
|210. |  | NEW ENGLAND ENERGY INCORPORATED                                 |  | USA                     
|211. |  | NEW ENGLAND HYDRO FINANCE COMPANY, INC.
(53.704%)               |  | USA                     
|212. |  | NEW ENGLAND HYDRO-TRANSMISSION CORPORATION
(53.704%)            |  | USA                     
|213. |  | NEW ENGLAND HYDRO-TRANSMISSION ELECTRIC COMPANY, INC.
(53.704%) |  | USA                     
|214. |  | NEW ENGLAND POWER COMPANY                                       |  | USA                     
|215. |  | NEWPORT AMERICA CORPORATION                                     |  | USA                     
|216. |  | NG CHICAGO I, LLC                                               |  | USA                     
|217. |  | NG JERSEY LIMITED                                               |  | Jersey                  
|218. |  | NG LEASING LIMITED                                              |  | England & Wales         
|219. |  | NG LUXEMBOURG 3 SARL                                            |  | Luxembourg              
|220. |  | NG LUXEMBOURG 4 SARL                                            |  | Luxembourg              
|221. |  | NG LUXEMBOURG 5 SARL                                            |  | Luxembourg              
|222. |  | NG LUXEMBOURG HOLDINGS LIMITED                                  |  | England & Wales         
|223. |  | NG LUXEMBOURG SA                                                |  | Luxembourg              



---

Exhibit 8

List of Subsidiaries

As at 31 March 2013



|     |  |                                                   |  |                         
|---- |  | ------------------------------------------------- |  | ------------------------
|     |  | Name                                              |  | Country of Incorporation
|224. |  | NG NOMINEES LIMITED                               |  | England & Wales         
|225. |  | NG PROCUREMENT HOLDINGS LIMITED                   |  | England & Wales         
|226. |  | NG VILLIERS LIMITED PARTNERSHIP                   |  | England & Wales         
|227. |  | NGC EMPLOYEE SHARES TRUSTEE LIMITED               |  | England & Wales         
|228. |  | NGC INDUS LIMITED                                 |  | England & Wales         
|229. |  | NGC TWO LIMITED                                   |  | England & Wales         
|230. |  | NGC ZAMBIA LIMITED                                |  | England & Wales         
|231. |  | NGET / SPT UPGRADES LTD (50%)                     |  | England & Wales         
|232. |  | NGG FINANCE (NO 1) LIMITED                        |  | England & Wales         
|233. |  | NGG FINANCE PLC                                   |  | England & Wales         
|234. |  | NGG TELECOMS HOLDINGS LIMITED                     |  | England & Wales         
|235. |  | NGG TELECOMS LIMITED                              |  | England & Wales         
|236. |  | NGM1 (GBR) LIMITED                                |  | Gibraltar               
|237. |  | NGNE LLC                                          |  | USA                     
|238. |  | NGP(IM7S) LIMITED                                 |  | Isle of Man             
|239. |  | NGP(IM7S) SUB LIMITED                             |  | England & Wales         
|240. |  | NGRID INTELLECTUAL PROPERTY LIMITED               |  | England & Wales         
|241. |  | NGT FIVE LIMITED                                  |  | Cayman Islands          
|242. |  | NGT FOUR LIMITED                                  |  | Cayman Islands          
|243. |  | NGT HOLDING COMPANY (ISLE OF MAN) LIMITED         |  | Isle of Man             
|244. |  | NGT LUXEMBOURG ONE LIMITED                        |  | England & Wales         
|245. |  | NGT ONE LIMITED                                   |  | England & Wales         
|246. |  | NGT TELECOM NO. 1 LIMITED                         |  | England & Wales         
|247. |  | NGT TELECOM NO. 2 LIMITED                         |  | England & Wales         
|248. |  | NGT THREE                                         |  | England & Wales         
|249. |  | NGT TWO LIMITED                                   |  | England & Wales         
|250. |  | NIAGARA MOHAWK ENERGY, INC.                       |  | USA                     
|251. |  | NIAGARA MOHAWK HOLDINGS, INC.                     |  | USA                     
|252. |  | NIAGARA MOHAWK POWER CORPORATION                  |  | USA                     
|253. |  | NM PROPERTIES, INC.                               |  | USA                     
|254. |  | NM URANIUM, INC.                                  |  | USA                     
|255. |  | NMP LIMITED                                       |  | England & Wales         
|256. |  | NORTH EAST TRANSMISSION CO., INC.                 |  | USA                     
|257. |  | NYSEARCH RMLD LLC (22.63%)                        |  | USA                     
|258. |  | NYSEARCH ROBOTICS LLC (14.59%)                    |  | USA                     
|259. |  | OPINAC NORTH AMERICA, INC.                        |  | USA                     
|260. |  | PATIENCE REALTY CORP.                             |  | USA                     
|261. |  | PCC LAND COMPANY, INC.                            |  | USA                     
|262. |  | PHILADELPHIA COKE CO., INC.                       |  | USA                     
|263. |  | PORT GREENWICH LIMITED                            |  | England & Wales         
|264. |  | PORT OF THE ISLANDS NORTH LLC                     |  | USA                     
|265. |  | PRUDENCE CORPORATION                              |  | USA                     
|266. |  | SCC UNO SA                                        |  | Chile                   
|267. |  | STARGAS NOMINEES LIMITED                          |  | England & Wales         
|268. |  | SUPERGRID ELECTRICITY LIMITED                     |  | England & Wales         
|269. |  | SUPERGRID ENERGY TRANSMISSION LIMITED             |  | England & Wales         
|270. |  | SUPERGRID LIMITED                                 |  | England & Wales         
|271. |  | TELECOM INTERNATIONAL HOLDINGS LIMITED            |  | England & Wales         
|272. |  | THAMESPORT INTERCHANGE LIMITED                    |  | England & Wales         
|273. |  | THE BROOKLYN UNION GAS COMPANY                    |  | USA                     
|274. |  | THE NARRAGANSETT ELECTRIC COMPANY                 |  | USA                     
|275. |  | THE NATIONAL GRID GROUP QUEST TRUSTEE COMPANY LTD |  | England & Wales         
|276. |  | THE NATIONAL GRID INVESTMENTS COMPANY             |  | England & Wales         
|277. |  | TRANSCO LIMITED                                   |  | England & Wales         
|278. |  | TRANSGAS, INC.                                    |  | USA                     
|279. |  | UNIT 40 SUBLESSOR LLC                             |  | USA                     
|280. |  | UPPER HUDSON DEVELOPMENT INC                      |  | USA                     



---

Exhibit 8

List of Subsidiaries

As at 31 March 2013



|     |  |                                            |  |                         
|---- |  | ------------------------------------------ |  | ------------------------
|     |  | Name                                       |  | Country of Incorporation
|281. |  | VALLEY APPLIANCE AND MERCHANDISING COMPANY |  | USA                     
|282. |  | VILLIERS FINANCE SA                        |  | Luxembourg              
|283. |  | WAYFINDER GROUP, INC.                      |  | USA                     
|284. |  | XOSERVE LIMITED (56.5%)                    |  | England & Wales         
|285. |  | YANKEE ATOMIC ELECTRIC COMPANY (34.5%)     |  | USA