HOW quickly City sentiment changes.

Cairn Energy, not so long ago one of the stock market's darlings, was savaged again yesterday by the money men.

The problem is the coveted but elusive Block 10 in Bangladesh.

The Bangladeshi government's indefinite postponement of awarding this acreage is seen as a major threat to the oil and gas independent's link-up with Shell.

There are worries that relations between Bangladesh's government and the Shell-Cairn joint venture have become distinctly frosty. And state-owned oil and gas company BOGMC's agreement on the reserves of Cairn's prized Sangu gas field is required before the ''daily contract quantity'' of gas to be delivered increases to the planned 200 million standard cubic feet per day.

Rumours that Shell is poised to pull out of Bangladesh may be mischief-making but, then again, they might reflect the international giant's displeasure with not for once getting what it wants.

But it is not all gloom and doom.

Sangu, which has proved one of the world's fastest offshore gas field developments, is up and running. Cairn has received payment for the first deliveries.

The different geology of Cairn's offshore acreage in Bangladesh should mean it has more potential than the onshore Halda field. Lessons will have been learned.

About three-and-a-half years ago, when Cairn shares were around 70p, chief executive Bill Gammell spelled out a vision in which Bangladesh was the key.

The company hit a gusher in Sangu and its shares rocketed.

The irrepressible Gammell remains upbeat about the prospects in offshore Bangladesh.

Cairn shares have been cut to about one-fifth of the peak they hit last year.

For the brave it might be a buying opportunity, but it is not for widows and orphans, or the faint-hearted.