Exhibit 8.1

|                                                                                                                               |                            | Country of
Incorporation |  | Trading
Name          
|------------------------------------------------------------------------------------------------------------------------------ | -------------------------- | ------------------------ |  | ----------------------
|Communications                                                                                                                 |                            |                          |  |                       
|Performance Analysis division                                                                                                  |                            |                          |  |                       
|Caw Networks, Inc                                                                                                              |                            | Delaware, USA            |  | Spirent Communications
|Spirent Communications (Scotland) Ltd*                                                                                         |                            | England                  |  | Spirent Communications
|Spirent Communications Inc:                                                                                                    |                            | Delaware, USA            |  | Spirent Communications
|                                                                                                                               | Calabasas, California, USA |                          |  |                       
|                                                                                                                               | Honolulu, Hawaii, USA      |                          |  |                       
|                                                                                                                               | Sunnyvale, California, USA |                          |  |                       
|                                                                                                                               | Eatontown, New Jersey, USA |                          |  |                       
|Spirent Communications of Ottawa Ltd                                                                                           |                            | Canada                   |  | Spirent Communications
|Spirent Communications (SW) Ltd*                                                                                               |                            | England                  |  | Spirent Communications
|Service Assurance division                                                                                                     |                            |                          |  |                       
|Spirent Communications of Rockville, Inc.                                                                                      |                            | Delaware, USA            |  | Spirent Communications
|Spirent Communications Ltd*                                                                                                    |                            | England                  |  | Spirent Communications
|Network Products                                                                                                               |                            |                          |  |                       
|Trading divisions of Spirent plc:
HellermannTyton:
Aldridge, West Midlands, UK
Plymouth, Devon, UK
Wythenshawe, Manchester, UK |                            |                          |  | HellermannTyton       
|HellermannTyton (Pty) Ltd                                                                                                      |                            | South Africa             |  | HellermannTyton       
|HellermannTyton S.A.                                                                                                           |                            | France                   |  | HellermannTyton       
|HellermannTyton AB                                                                                                             |                            | Sweden                   |  | HellermannTyton       
|HellermannTyton GmbH                                                                                                           |                            | Austria                  |  | HellermannTyton       
|HellermannTyton GmbH                                                                                                           |                            | Germany                  |  | HellermannTyton       
|HellermannTyton Ltda                                                                                                           |                            | Brazil                   |  | HellermannTyton       
|HellermannTyton Pte Ltd                                                                                                        |                            | Singapore                |  | HellermannTyton       
|HellermannTyton Data Ltd*                                                                                                     |                            | England                  |  | HellermannTyton       
|HellermannTyton Corporation                                                                                                    |                            | Delaware, USA            |  | HellermannTyton       
|Tyton Company of Japan Ltd* (Associate)                                                                                        |                            | Japan                    |  | HellermannTyton       
|Systems                                                                                                                        |                            |                          |  |                       
|PG Drives Technology Ltd                                                                                                       |                            | England                  |  | PG Drives Technology  
|PG Drives Technology Inc                                                                                                       |                            | Delaware, USA            |  | PG Drives Technology  
|Spirent Systems San Diego Inc                                                                                                  |                            | Delaware, USA            |  | Spirent Systems       
|Spirent Systems Wichita Inc                                                                                                    |                            | Delaware, USA            |  | Spirent Systems       
|WPDS Software Ltd*                                                                                                             |                            | England                  |  | Spirent Systems       
|The Flight Data Company Ltd                                                                                                    |                            | England                  |  | Spirent Systems       
|Spirent Systems (Ottawa) Ltd                                                                                                   |                            | Canada                   |  | Spirent Systems       
|Financial                                                                                                                      |                            |                          |  |                       
|Spirent BV                                                                                                                     |                            | The Netherlands          |  | Non-trading           
|Spirent GmbH                                                                                                                   |                            | Germany                  |  | Non-trading           
|Spirent Holdings Corporation                                                                                                   |                            | Delaware, USA            |  | Non-trading           
|Interconnection Joint Venture                                                                                                 |                            |                          |  |                       
|WAGO Contact SA                                                                                                                |                            | Switzerland              |  | WAGO                  
|WAGO Kontakttechnik GmbH                                                                                                       |                            | Germany                  |  | WAGO                  

This
list of subsidiaries omits certain subsidiaries that, in the aggregate, would not be a "significant subsidiary" as of December 31, 2002.

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