Construction costs that have risen by one-third from their pre-pandemic levels sank a proposed merger of Rich List developer Tim Gurner’s company and fellow Rich Lister Andrew Roberts’ building contractor Roberts Co, a source with the knowledge of the discussion said.

A lack of “chemistry” between Mr Gurner – known for luxury residential developments, a growing build-to-rent portfolio and his luxury health club – and Mr Roberts, as well as an unresolved question of the relative values of their two businesses also hindered the transaction, another source said.