Prudential, Aviva and Legal & General made gains as FCA boss Martin Wheatley admitted that the way it announced the inquiry into 30 million financial policies sold between the 1970s and the turn of the millennium was not its "finest hour".
The wider FTSE 100 Index was also on the front foot, up 54.2 points to 6652.6, thanks to gains from heavyweight mining giant BHP Billiton after it said it was considering a spin-off of unwanted assets worth an estimated £11 billion.
Blue-chip stocks were also propelled upward on the back of strong overnight gains on Wall Street and Asia after an indication from the US Federal Reserve that interest rates will need to remain low.
Markets in Germany and France also made gains while New York's Dow Jones Industrial Average was ahead at the time of the close of play in the City.
On currency markets, sterling held firm at 1.66 US dollars and 1.21 euros.
In London, insurance stocks were among those making gains as the furore surrounding the FCA probe failed to die down, with even George Osborne weighing in to the controversy.
The Chancellor said he was "profoundly concerned" by the City watchdog's botched announcement and demanded a thorough inquiry.
It saw the FCA first disclose details of its probe into the industry in a newspaper interview, then wait six hours after the Stock Market opened before clarifying the scope of its inquiry.
But Mr Wheatley told BBC Radio 4's Today programme he had a "big job to do" and was not planning to resign over the episode
While the regulator was under pressure, insurers rose, with Prudential up nearly 4%, or 48.5p, to 1317p, while Legal & General added 7p to 211.7p and Aviva was up 15.1p to 492.1p.
BHP added 38p to 1882p after confirming a potential demerger of assets such as aluminium and nickel into a separate company.
Babcock International made strong gains for the second session in a row, up 3% or 40p to 1387p.
It came after a broker upgrade in light of an announcement the group, together with US partner Fluor, had been appointed preferred bidder for a £7 billion contract to manage the decommissioning of 12 UK nuclear sites.
The biggest FTSE 100 risers were Aberdeen Asset Management, up 26.2p to 416.5p, ARM Holdings up 49p to 1047p, Sports Direct up 40.5p to 892.5p and Prudential up 48.5p to 1317p.
The biggest FTSE 100 fallers were Sainsbury's, down 6.6p to 309.5p, Pearson down 19p to 1044p, Morrisons down 2.2p to 210.8p and Mondi down 8p to 1041p.