Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
SR Maunsell carriage
Table title:
Preservation
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Origin </th><th colspan=1 rowspan=1 > Number </th><th colspan=1 rowspan=1 > Type </th><th colspan=1 rowspan=1 > Location </th><th colspan=1 rowspan=1 > Notes </th><th colspan=1 rowspan=1 > Photograph </th></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 5644 </td><td colspan=1 rowspan=1 > Corridor Composite </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1930, Stored awaiting restoration. Restriction '4' coach originally assigned to set 195 before going to set 455 in 1956 and set 195 in 1957, it was withdrawn in 1961. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 7866 </td><td colspan=1 rowspan=1 > Dining Saloon </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1927. Originally numbered 1365, Stored awaiting overhaul. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 7864 </td><td colspan=1 rowspan=1 > Kitchen First </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1932. Stored undercover. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 6575 </td><td colspan=1 rowspan=1 > Brake Corridor Composite </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1929. Stored awaiting a fairly major overhaul particularly at the brake end. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 4444 </td><td colspan=1 rowspan=1 > Brake Unclassed open </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1933. Out of service awaiting restoration. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 4441 </td><td colspan=1 rowspan=1 > Brake Unclassed open </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1933. Awaiting overhaul with a seriously damaged underframe but a reasonably complete body. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 6686 </td><td colspan=1 rowspan=1 > Brake Corridor Composite </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1935. Operational, won the 'Highly Commended Coach of the Year' award for 1998/99. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1336 </td><td colspan=1 rowspan=1 > Third Open </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1933. In service and used on passenger trains. </td><td colspan=1 rowspan=1 > 1336smallRSBR.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1309 </td><td colspan=1 rowspan=1 > Third Open </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1935. In service and used on passenger trains. </td><td colspan=1 rowspan=1 > 1309smallRSBR.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 2356 </td><td colspan=1 rowspan=1 > Corridor Third </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1931. Awaiting overhaul. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 3687 </td><td colspan=1 rowspan=1 > Brake Third Corridor </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1931. Undergoing overhaul and conversion back to original condition, after a BR rebuild and subsequent departmental conversion. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 3724 </td><td colspan=1 rowspan=1 > Brake Third Corridor </td><td colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1930. Stripped out and rebuilt for use on Chipmans weed-killer train. </td><td colspan=1 rowspan=1 > 3724smallRSBR.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td class="highlighted"  colspan=1 rowspan=1 > 4922 </td><td class="highlighted"  colspan=1 rowspan=1 > Post Office Sorting Van </td><td class="highlighted"  colspan=1 rowspan=1 > Bluebell Railway </td><td colspan=1 rowspan=1 > Built in 1939. Awaiting Restoration. Restriction '4' coach originally in set 207, it was withdrawn in 1977. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 3725 </td><td colspan=1 rowspan=1 > Brake Third Corridor </td><td colspan=1 rowspan=1 > Colne Valley Railway </td><td colspan=1 rowspan=1 > Built in 1930. Under frame only used as a crane runner. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > MAT 94117 (Not SR number) </td><td colspan=1 rowspan=1 > Not Known </td><td colspan=1 rowspan=1 > Gloucestershire and Warwickshire Railway </td><td colspan=1 rowspan=1 > Under frame only </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1019 </td><td colspan=1 rowspan=1 > Corridor Third </td><td colspan=1 rowspan=1 > Isle of Wight Railway </td><td colspan=1 rowspan=1 > Built in 1933. Under frame only. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 5618 </td><td colspan=1 rowspan=1 > Corridor Composite </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1931. In service and used on passenger trains. </td><td colspan=1 rowspan=1 > SOUTHERN CK 5618.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 7400 </td><td colspan=1 rowspan=1 > Corridor First </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1929. Under frame only. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 7798 </td><td colspan=1 rowspan=1 > Open Second </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1931. Under frame only. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 5153 </td><td colspan=1 rowspan=1 > Corridor Composite </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1928. Awaiting restoration. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 4432 </td><td colspan=1 rowspan=1 > Brake Unclassed Open </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1933. In service and used on passenger trains. </td><td colspan=1 rowspan=1 > SR4432.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 4443 </td><td colspan=1 rowspan=1 > Brake Unclassed Open </td><td colspan=1 rowspan=1 > Kent and East Sussex Railway </td><td colspan=1 rowspan=1 > Built in 1933. In service and used on passenger trains. </td><td colspan=1 rowspan=1 > Maunsell Carriage 4443 K&ESR 2016.JPG </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td class="highlighted"  colspan=1 rowspan=1 > 4920 </td><td class="highlighted"  colspan=1 rowspan=1 > Post Office Sorting Van </td><td class="highlighted"  colspan=1 rowspan=1 > Nene Valley Railway </td><td colspan=1 rowspan=1 > Built in 1939. Stored. Restriction '4' coach. </td><td colspan=1 rowspan=1 > - </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td class="highlighted"  colspan=1 rowspan=1 > 4958 </td><td class="highlighted"  colspan=1 rowspan=1 > Post Office Tender Van </td><td class="highlighted"  colspan=1 rowspan=1 > Pontypool and Blaenavon Railway </td><td colspan=1 rowspan=1 > Built in 1939. Awaiting Restoration. Restriction '4' coach. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 3690 </td><td colspan=1 rowspan=1 > Brake Third Corridor </td><td colspan=1 rowspan=1 > Robertsbridge railway station </td><td colspan=1 rowspan=1 > Built in 1931. Awaiting Restoration. Restriction '0' originally in set 216 before being loose in 1960 withdrawn in 1961. </td><td colspan=1 rowspan=1 > Maunsell 3690 </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1323 </td><td colspan=1 rowspan=1 > Third Open </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1932. Under Restoration, exterior mostly complete, interior incomplete. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1346 </td><td colspan=1 rowspan=1 > Third Open </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1933. Under Restoration. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 1381 </td><td colspan=1 rowspan=1 > Third Open </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1930. Under Restoration. Restriction '4' originally loose it was withdrawn in 1961. Restoration taking place at Ramparts, Derby. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 2768 </td><td colspan=1 rowspan=1 > Brake Third Corridor </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1932. Under frame only. Restriction '4' originally in set 232 it was withdrawn in 1962. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 6699 </td><td colspan=1 rowspan=1 > Driving Brake Composite </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1935. Awaiting Restoration. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 6697 </td><td colspan=1 rowspan=1 > Driving Brake Composite </td><td colspan=1 rowspan=1 > Swanage Railway </td><td colspan=1 rowspan=1 > Built in 1935. Awaiting restoration. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 5600 </td><td colspan=1 rowspan=1 > Corridor Composite </td><td colspan=1 rowspan=1 > Wishaw </td><td colspan=1 rowspan=1 > Built in 1931. Awaiting restoration. </td><td colspan=1 rowspan=1 >  </td></tr>
<tr> <td colspan=1 rowspan=1 > Southern Railway </td><td colspan=1 rowspan=1 > 185392 (Not SR number) </td><td colspan=1 rowspan=1 > Not Known </td><td colspan=1 rowspan=1 > Swindon and Cricklade Railway </td><td colspan=1 rowspan=1 > Under frame only </td><td colspan=1 rowspan=1 >  </td></tr>
</table>
Question:
What location were the POSVs preserved? 
Answer:
Two POSVs, the 4922 at the Bluebell Railway and the 4920 the Nene Valley Railway, and one POTV, 4958, at the Pontypool and Blaenavon Railway, were preserved.