From this summer when the Health Bill becomes law masons lighting up a cigarette in an enclosed workshop or inside an enclosed structure being built or renovated could face an instant £30 fine (£50 if it is not paid within 15 days) and firms could be fined £2,500.

Operatives will not be able to go to a specified smoking area for a puff, either, because the law, as currently proposed, prohibits the provision of such areas. Firms will be required to put up notices saying so - or be fined £200 for not doing so.

According to research by company law specialists Croner, half the 72% of companies who think they are already complying with the proposed smoking ban are not.

They say companies should ban smoking ahead of the change in the law and offer support to employees who want to give up smoking.