NP fell 32p to 527p and PG 12p to 536p; both touched 510p. Since Southern Company, the US group, disclosed its ambitions towards NP the shares have fallen from 605p.
The highly-charged decision destroyed a stock market rally. It had, without much conviction, overcome worries about the local election results and today's US payroll figures. Even worse-than-forecast results from the Kwik Save food discount chain failed to rattle sentiment. But the Whitehall block and a surprise profit warning from the Great Universal Stores mail order and retail giant proved too much.
If the BT bombshell - the end of merger talks with Cable & Wireless - had appeared during trading shares could have gone into free fall. It came after hours although, with BT down 8p at 352p, some clever souls managed to anticipate the break-down. The shares are likely to fall sharply today as the talks have illustrated just how desperate BT is for a Cable- style merger. Cable rose 3.5p to 524p and, after initial uncertainty, is likely to strengthen on takeover hopes.
The FT-SE 100 index ended 29.6 points down at 3,776.4 in often brisk trading. The supporting index lost 2.4 to 4,537.7. Yet in early trading it had all looked so different. Two programme trades helped lift Footsie 23.4; so the downturn wiped more than 50 points from the index.
The generators veto, which can hardly support the case for investing in Railtrack even with the sort of yield reserved for the most highly speculative share, is the third blow electricities have suffered in less than 18 months.
The Littlechild debacle in January last year sent the sector into a spin and last month came the surprise block on the generators' bids for two distributors.
The decision to make the generators bid-proof will almost certainly reduce the chances of the cash-rich duo indulging in generous dividend payments and share buy-backs.
It takes a lot to fuse the market's takeover excitement and in the volatile atmosphere some distributors, such as London Electric, moved ahead in the belief the Government's actions could encourage overseas predators. London gained 13p to 826p.
Commercial Union, the insurance group, recaptured takeover fever. The shares touched 600p, closing up 9p at 590p as stories circulated of a bid, with France's Societe Generale and Germany's Allianz, the names in the frame.
Ladbroke, the betting and hotel group, had another high turnover session although the shares only managed a 2p gain to 195p. Barclays de Zoete Wedd was said to have put a 210p valuation on them,
GUS fell 30p to 687p and Kwik Save 40p to 428p. Argos, after a bright start which took the price to 667p, relapsed to 648p, down 1p. It is said its offer for one of the Signet jewellery chains has been turned down; Signet fell 3.25p to 26.75p. Body Shop International gained 19p to 179p on the 55 per cent dividend increase.
British Airways rose 4p to 524p. Reports that orders for new aircraft for regional routes had been pulled back were seen as reducing rights issue pressure.
Regal Hotels made a strong return. Suspended at 44p since January when it opened talks to buy the White Hart hotels chain the shares stretched to 56p in busy trading. The convertibles, offered at 100p, went to 119p.
The White Hart deal represents the first big disposal from the Forte empire since Granada gained control. Regal paid pounds 120m for 60 White Hart properties, increasing its chain to 83.
Ramco Energy, with oil and gas interests in the former Soviet Union, firmed to 595p as Henderson Crosthwaite placed 960,000 shares at 592p.
Brightstone Properties had an eventful time. It announced a consortium, including the ubiquitous Luke Johnson, would subscribe for 300,000 shares and the group saw its future outside the property industry. Mr. Johnson would join the board.
In less than an hour Clarke, Nickolls & Coombs, once a sweetmaker now a property play, produced a 124p share exchange offer with Brightstone shareholders representing 14.4 per cent accepting. CNC said other shareholders with 29.3 per cent had "signed letters of support". The action left Brightstone up 18p at 120p and CNC unchanged at 7.75p.