Bouygues, which is helping build part of the HS2 railroad in the Chilterns, saw sales and profits increase to pre-pandemic levels in the first half of the year after being ravaged by lockdowns last year.
The French giant, whose UK business had sales of £ 400m (£ 472m) after a loss of £ 176m (£ 151m) last time.
Bouygues, whose activities range from construction to media and telecommunications, said revenue in its largest business, construction, rose 18% to 12.6 billion from the tough bans imposed since the pandemic last March.
It posted an operating profit of € 83 million (£ 71 million) compared to a loss of € 437 million.
It added that it has appointed a new construction chief Pascal Minault to replace Philippe Bonnave, who has taken on a new role elsewhere in his construction business.
Bouygues net debt was € 2.8 billion (£ 2.4 billion) in the first half of the year, an improvement of € 1.1 billion (£ 940 million) from June 2020.