UK institutional shareholders are backing the management of plasterboard specialist BPB in refusing to talk to hostile suitor Saint Gobain, at least until the French glassmaker significantly improves its offer.

Sandy Black, head of equities at Insight Investment, which owns 4.6% of BPB, said: "We think that Saint Gobain's bid of 720p undervalues the company, and we back the management's rejection of the bid."