Workers building the £4bn fifth terminal at Heathrow Airport have gone on strike, for the second time in two months.
Hundreds of scaffolders, labourers and others manned picket lines today at the start of the four-day stoppage.
There will be an overtime ban over the weekend and another strike on Monday as part of campaign for a £1-an-hour rise in bonus pay.
Employers Laing O’Rourke said its offer of an extra 67p per hour would be withdrawn if the strike went ahead.
But the GMB union said the offer had not been received in writing.