GrandMet jumped 17.5p to 603.5p and its would-be partner, Guinness, 15p to 605p.
But it was Allied Domecq, the Beefeater gin and Teacher's whisky group which would be a casualty of any GrandMet/Guinness deal, which stole the show.
As the market closed there was a sudden rush to buy and Allied, which had been bumping along near its all-time low, enjoyed the distinction of heading the blue-chip leader board with a 13.5p gain to 428p.
The sudden interest in struggling Allied prompted suggestions it could be dragged into the GrandMet/Guinness imbroglio or may have attracted the attention of Seagram, the Canadian group which would be hit by the creation of a new and powerful spirit giant.
There was also talk of Allied linking with other spirits group such as Pernod Ricard of France or the unquoted Bacardi rum business.
In early trading Allied shares were friendless, off 7p. The sudden buying enthusiasm took Seaq recorded turnover to approaching 13.5 million.
Mr Arnault's LVMH luxury goods group, which runs the Moet Hennessy Champagne and Cognac group with Guinness as a minority shareholder, seems to have acquired 126 million GrandMet shares, most at 630p. It is thought the vast majority came from Mercury Asset Management.
The staggering pounds 790m raid lifts LVMH's stake to 6.29 per cent. There is speculation it intends to take its shareholding to 15 per cent.
Idea is to put pressure on the proposed GrandMet/Guinness deal to form GMG Brands. Mr Arnault is against the alliance and favours a three-way link involving the GrandMet and Guinness wine and spirit operations and Moet Hennessy.
LVMH has 14 per cent of Guinness. At one time it had 24 per cent. In January the French group sold around 7 per cent at 414p. It now has 14.2 per cent.
The rest of the market was made to look a little foolish by New York. It spent much of the session wallowing in despair, fretting about the Budget, interest rates and today's futures and options expiry.
Then New York opened on a surprisingly positive note. And Footsie, which had been down 27.9 points, scampered to catch up, ending 3.3 lower at 4,653.7.
BICC, the cables and construction group, eased to 181.5p as Credit Lyonnais Laing and NatWest Securities made cautious noises. Imperial Chemical Industries, up 26p to 859.5p, was buoyed by US buying and Lloyds TSB gained 14.5p to 620p with SBC Warburg thought to have lifted its profits estimates and put a buy sign on the shares. BT buzzed 4.5p higher to 455.5p, anticipating MCI merger benefits.
Former building societies Alliance & Leicester and Halifax moved ahead in anticipation of Monday's elevation to Footsie. A&L rose 11p to 599p and Halifax 10.5p to 745p.
BSkyB, the satellite broadcaster, had another downbeat session, falling 13.5p to 508p. RioTinto's copper-inspired run came to an end with the shares off 19p to 1,065.5p.
Kalamazoo, the computer group shaded 3p to 84p as would-be bidder Lynx, up 1.5p to 102.5p, walked away. McDonnell Information Systems gave up 6p to 28p as it produced its umpteenth profit warning.
RJB Mining fell 15.5p to 346p. A profits downgrading by the company's stockbroker, BZW, did the damage. Although the broker is sticking with its buy advice it is said to have lowered this year's estimate from pounds 192.3m to pounds 185.1m. In December RJB crashed 112.5p to 372.5p when BZW cut last year's forecast to pounds 192m. In the event the company produced pounds 189.2m.
Birmingham City, the football club, held at 38p. David Sullivan and the Gold brothers, who control the club, have picked up a further 50,000 shares at 37p. The were sold to investors at 50p in February.
Mid States, the US car parts group which reached 122p a few years ago, fell 6.25p to 12p following a trading warning. West 175 Enterprises, a US TV producer, added 5p to 85p after clinching a deal to develop and produce BBC programmes.
Owen & Robinson, the retail chain, firmed to 11p. In a share exchange it is bidding 63p a share for Ofex traded Capolito Roma, a clothing and footwear retailer, up 6p to 60p. Michael Abrams of Capolito will become chief executive of the enlarged group.