1 London Electricity plc , a 1 April 1990 to 31 March 1992 , a 855.300 MW , , b 1 April 1992 to 30 September 1992 , b 846.300 MW , , c 1 October 1992 to 31 March 1995 , c 821.800 MW , , d 1 April 1995 to 30 April 1995 , d 785.800 MW , , e 1 May 1995 to 31 March 1996 , e 738.800 MW , , f 1 April 1996 to 30 June 1996 , f 813.900 MW , , g 1 July 1996 to 31 March 1998 , g 771.900 MW , 2 SEEBOARD plc , a 1 April 1990 to 31 March 1992 , a 709.899 MW , , b 1 April 1992 to 30 September 1992 , b 702.429 MW , , c 1 October 1992 to 31 March 1995 , c 682.094 MW , , d 1 April 1995 to 30 April 1995 , d 652.214 MW , , e 1 May 1995 to 31 March 1996 , e 613.204 MW , , f 1 April 1996 to 30 June 1996 , f 675.537 MW , , g 1 July 1996 to 31 March 1998 , g 640.677 MW , 3 Southern Electric plc , a 1 April 1990 to 31 March 1992 , a 1060.572 MW , , b 1 April 1992 to 30 September 1992 , b 1049.412 MW , , c 1 October 1992 to 31 March 1995 , c 1019.032 MW , , d 1 April 1995 to 30 April 1995 , d 974.392 MW , , e 1 May 1995 to 31 March 1996 , e 916.112 MW , , f 1 April 1996 to 30 June 1996 , f 1009.236 MW , , g 1 July 1996 to 31 March 1998 , g 957.156 MW , 4 South Western Electricity plc , a 1 April 1990 to 31 March 1992 , a 487.521 MW , , b 1 April 1992 to 30 September 1992 , b 482.391 MW , , c 1 October 1992 to 31 March 1995 , c 468.426 MW , , d 1 April 1995 to 30 April 1995 , d 447.906 MW , , e 1 May 1995 to 31 March 1996 , e 421.116 MW , , f 1 April 1996 to 30 June 1996 , f 463.923 MW , , g 1 July 1996 to 31 March 1998 , g 439.983 MW , 5 Eastern Electricity plc , a 1 April 1990 to 31 March 1992 , a 1171.761 MW , , b 1 April 1992 to 30 September 1992 , b 1159.431 MW , , c 1 October 1992 to 31 March 1995 , c 1125.866 MW , , d 1 April 1995 to 30 April 1995 , d 1076.546 MW , , e 1 May 1995 to 31 March 1996 , e 1012.156 MW , , f 1 April 1996 to 30 June 1996 , f 1115.043 MW , , g 1 July 1996 to 31 March 1998 , g 1057.503 MW , 6 East Midlands Electricity plc , a 1 April 1990 to 31 March 1992 , a 769.770 MW , , b 1 April 1992 to 30 September 1992 , b 761.670 MW , , c 1 October 1992 to 31 March 1995 , c 739.620 MW , , d 1 April 1995 to 30 April 1995 , d 707.220 MW , , e 1 May 1995 to 31 March 1996 , e 664.920 MW , , f 1 April 1996 to 30 June 1996 , f 732.510 MW , , g 1 July 1996 to 31 March 1998 , g 694.710 MW , 7 Midlands Electricity plc , a 1 April 1990 to 31 March 1992 , a 829.641 MW , , b 1 April 1992 to 30 September 1992 , b 820.911 MW , , c 1 October 1992 to 31 March 1995 , c 797.146 MW , , d 1 April 1995 to 30 April 1995 , d 762.226 MW , , e 1 May 1995 to 31 March 1996 , e 716.636 MW , , f 1 April 1996 to 30 June 1996 , f 789.483 MW , , g 1 July 1996 to 31 March 1998 , g 748.743 MW , 8 South Wales Electricity plc , a 1 April 1990 to 31 March 1992 , a 299.355 MW , , b 1 April 1992 to 30 September 1992 , b 296.205 MW , , c 1 October 1992 to 31 March 1995 , c 287.630 MW , , d 1 April 1995 to 30 April 1995 , d 275.030 MW , , e 1 May 1995 to 31 March 1996 , e 258.580 MW , , f 1 April 1996 to 30 June 1996 , f 284.865 MW , , g 1 July 1996 to 31 March 1998 , g 270.165 MW , 9 Manweb plc , a 1 April 1990 to 31 March 1992 , a 496.074 MW , , b 1 April 1992 to 30 September 1992 , b 490.854 MW , , c 1 October 1992 to 31 March 1995 , c 476.644 MW , , d 1 April 1995 to 30 April 1995 , d 455.764 MW , , e 1 May 1995 to 31 March 1996 , e 428.504 MW , , f 1 April 1996 to 30 June 1996 , f 472.062 MW , , g 1 July 1996 to 31 March 1998 , g 447.702 MW , 10 Yorkshire Electricity Group plc , a 1 April 1990 to 31 March 1992 , a 701.346 MW , , b 1 April 1992 to 30 September 1992 , b 693.966 MW , , c 1 October 1992 to 31 March 1995 , c 673.876 MW , , d 1 April 1995 to 30 April 1995 , d 644.356 MW , , e 1 May 1995 to 31 March 1996 , e 605.816 MW , , f 1 April 1996 to 30 June 1996 , f 667.398 MW , , g 1 July 1996 to 31 March 1998 , g 632.958 MW , 11 Northern Electric plc , a 1 April 1990 to 31 March 1992 , a 453.309 MW , , b 1 April 1992 to 30 September 1992 , b 448.539 MW , , c 1 October 1992 to 31 March 1995 , c 435.554 MW , , d 1 April 1995 to 30 April 1995 , d 416.474 MW , , e 1 May 1995 to 31 March 1996 , e 391.564 MW , , f 1 April 1996 to 30 June 1996 , f 431.367 MW , , g 1 July 1996 to 31 March 1998 , g 409.107 MW , 12 NORWEB plc , a 1 April 1990 to 31 March 1992 , a 718.452 MW , , b 1 April 1992 to 30 September 1992 , b 710.892 MW , , c 1 October 1992 to 31 March 1995 , c 690.312 MW , , d 1 April 1995 to 30 April 1995 , d 660.072 MW , , e 1 May 1995 to 31 March 1996 , e 620.592 MW , , f 1 April 1996 to 30 June 1996 , f 683.676 MW , , g 1 July 1996 to 31 March 1998 , g 648.396 MW ,