Speaking at an oil industry conference in Norway he said the group's much-vaunted ambition to produce 320,000 barrels a day would have to be put back until 1999.
Although this year's output had been rather lacklustre Enterprise had appeared confident as recently as September that it was still on course to meet its signalled production levels. But Mr Jungels said next year's output was likely to be similar to this year's. His comments were immediately viewed as a disguised profit warning. They flowed over to Lasmo, off 6p at 275p.
Enterprise has had a heady stock market run. At one time shares were riding at 729.5p with a range of bullish stories going the rounds. They were pulled back as the market came off the boil but were still regarded as one of the better performing blue-chips.
The oil group's fall from grace was a major factor in Footsie's 21.6 points fall to 4,845.4.
But at least Enterprise's negative contribution was genuine; Williams' 37p advance to 390p was entirely fictional.
For most of the session the fire protection and security group was traded between 346p and 351p. Then as the market closed there was an order-book trade at 390p for just 1,000 shares. Clearly some mistake. Even so Williams was elevated to top of the blue-chip leader board with the alleged 390p close, representing a 10.5 per cent gain, used in the final Footsie calculation.
The latest order-driven fiasco comes as pressure mounts for the Stock Exchange to make the system more friendly to agency brokers and small investors.
The market remained preoccupied with Far Eastern affairs. Another rally in Tokyo was undermined by a further setback in Hong Kong and suggestions the Japanese market was set for a bumpy ride overnight.
Hopes of a financial deal still drifted around with National Westminster Bank up 12.5p to 883p. There is a growing conviction that NatWest has re-opened talks with Deutche Morgan Grenfell for the sale of its securities operation.
Vodafone misdialled, falling 15.5p to 341.5p. A series of price cuts triggered suggestions it was starting a mobile telephone war. The company denied it was launching a price-cutting campaign. It claimed the market should be growing at a faster rate and "it is appropriate for the market leader to lead this new phase of growth". Orange was caught on the Vodafone line, giving up 9p to 242p.
Cadbury Schweppes shrugged off the appearance of another lemonade rival in the US. PepsiCo is launching a lemonade-style soft drink to challenge Cadbury's Seven-up and Coco-Cola's Sprite. Cadbury shares ended 1.5p higher at 614.5p.
The latest takeover block by Margaret Beckett, President of the Board of Trade, lowered Sears 3.5p to 54.5p. Sears, denied the chance of selling Freemans to Littlewoods, said it intends to demerge its home shopping operation with a cash hand- back to shareholders.
Northern Ireland Electricity, another handing over cash, improved 14.5p to 488.5p. Its exercise is, in effect, part of a name change - to Viridian.
Talk of bids, probably a management buy-out, gave Racal Electronic a 9.5p boost to 224p.
Billiton fell 5p to 170p despite warming noises from Societe Generale Strauss Turnbull. Although the securities house regards the metals group as a buy it has lowered its earnings forecasts.
Ronson, the luxury goods group, lost an early gain to stick at 11p after saying takeover talks with third parties continue. The shares have fallen from more than 20p since August when negotiations were revealed.
Ilion, the computer distribution group, was the worst casualty, falling 90p to 172.5p after warning that year's profits would not meet hopes of around pounds 8m. The group, formerly Persona, expects an out-turn in the pounds 6m to pounds 6.5m range.
Costain, the civil engineer, lost 3.5p to 32.5p, lowest since its return. Majestic Wine bubbled 11p to a 320p peak on Christmas sales hopes and expectations of cheerful interim figures next week.