The excitement began when some traders asked whether the group would achieve the market's undemanding profit forecast of pounds 367m, representing a humble pounds 3.7m advance on the previous year.
Then Kleinwort Benson added to the anxiety by cutting its current year profits estimate and describing the shares as a short-term sell. Analysts James Dodd and John Karidis reduced their forecast by pounds 20m to pounds 466m.
Such behaviour did not rest easily with a highly-rated share, even if Kleinwort said the medium-term outlook is far from gloomy. But the securities house frets about increased competition hitting margins and mitigating the benefits of sales growth.
Vodafone has long enjoyed a strong US following, partly because its shares are on a lower rating than similar American communication groups. At the last count, 33.6 per cent of its capital was held through US ADRs and with a number of US investment groups displaying interest in the shares, the total transatlantic shareholding could be more than 40 per cent.
The debate over Vodafone came as its big UK rival, Cellnet, was caught by a Whitehall decision that appeared to rule out BT buying out the minority shareholding owned by the Securicor group.
Securicor, owning 40 per cent of Cellnet with BT accounting for 60 per cent, said it was "considering all its options" after the Government said it was not willing at present to allow BT to take full control. Securicor ordinary shares fell 42p to 1,543p, the 'A' shares 7p to 1,000p and Security Services, controlled by Securicor and with a direct Cellnet involvement, 37p to 863p.
The rest of the market had a volatile session with the FT-SE 100 index performing its own roller-coaster as New York made an uncertain start.
Through most of the session, the index held on to modest gains but when the Dow Jones Average slumped 40 points in its first 15 minutes of trading, shares took fright and Footsie lost 12 points. New York rallied, dragging the index up 8.7. It closed with a 4.4 gain at 3,345.0, highest since February last year.
New York's disjointed performance stemmed from unexpectedly weak US employment figures, producing worries of a recession. Then thoughts of lower interest rates calmed the atmosphere.
The poor jobs figures and other recessionary indicators prompted a US regional bank, the Southwest Bank of St Louis, renowned for being the first to jump, to cut its prime rate.
With Swiss Bank Corporation moving even closer to capturing SG Warburg, up 28p at 768p, speculative attention returned to Kleinwort, with Dresdner, the German bank, reappearing as the favourite to pounce. The shares rose 19p to 680p. Hambros, up 11p to 215p, and Wintrust, 12p to 225p, were also on buyers' lists.
The Warburg advance was probably a play on the terms which, although there is more than two months to wait before the proceeds are distributed, equate to 790p.
Arjo Wiggins Appleton, the packaging and paper group, slipped 6.5p to 263.5p as Kleinwort trimmed its forecast by pounds 10m to pounds 260m. Rexam, formerly Bowater, continued to enjoy its new name, up 9p to 490p. Argyll, the Safeway supermarket chain, dipped 4p to 331p with James Capel negative, but RTZ, helped by firmer copper prices and Barclays de Zoete Wedd support, improved 11p to 823p.
WPP, the advertising group, slipped 3p to 128p on its trading statement. Turnover was again high.
ABN Amro Hoare Govett was thought to have taken a negative stance on Wolseley, the building materials group which must be suffering as US building margins are squeezed. The shares fell 9p to 351p. Earlier this year, they touched 400p. Caradon was caught up in the depression, falling 10p to 250p.
Medeva dipped 2.5p to 245.5p as the market continued to await the signalled Fisons strike. A bid price of 260p seems to have become the popular guess against earlier hopes of 300p. Fisons dipped 2p to 172p. Glaxo Wellcome continued to feel the pinch of bearish US tip-sheet comment, off 2.5p to 720.5p.
Hi-tech, the sports shoe group, gave up 5.5p to 26p as three directors quit.
Gowrings, the Burger King operator and car dealer, rose 4p to 75p following an upbeat trading statement; securities house Brown Shipley expects a profit recovery to pounds 750,000 this year. Continental Foods, a snack food group, rose 7p to 78p in belated response to Henderson Crosthwaite forecasts.
Rutland Trust sold its remaining 49 per cent of a Yorkshire soft drinks business to Cott, the Canadian group, for pounds 4.25m. Last year, Cott paid pounds 6m for the other 51 per cent. Rutland, with a cash pile of pounds 20m, held at 26p. Capital Industries, where Rutland has a 42 per cent interest, slipped 2p to 146p after it shelved plans to demerge its financial services side.
o Gander, the old gold explorer traded on the 4.2 share market, continues to attract support. Greig Middleton, advising shareholders to take up a pounds 7m cash call, says the shares will have an asset backing of 20p by 1997 when profits will top pounds 1m.
The company, run by the Vaughan brothers who founded the Juliana's leisure group which was acquired by Wembley six years ago, concentrates on letting residential property in Kensington and Chelsea. The rights are at 8.5p against a market price of 7.75p. A full listing is planned next year.
o Harmony Property, where the Perloff family has acquired a 5.5 per cent interest, remains the subject of speculation with talk another share build up is under way. Identity of a big buyer earlier this week has yet to be disclosed. The shares held at 4.5p.