Brian Boehmer, partner at Lockton UK’s global professional and financial risks arm, blamed the sheer number of claims made against advisers in recent years for the cost increase, and said while premiums will unlikely return to former levels they will soon "level out".
Mr Boehmer dismissed the commonly held belief that the increase in compensation limits that happened earlier this year was behind the change to PI cost and said market trends would have always led to this outcome.
In April the Financial Conduct Authority increased the ombudsman's award limit from £150,000 to £350,000, accompanied by a forecast from the PI market that the rise could push up premiums by 500 per cent in a "worst-case" scenario.
Since then some advisers have seen their PI premiums increase exponentially, with the Personal Finance Society last week confirming one adviser had reported the cost of his insurance had risen from £6,700 to £27,000.
I think advisers should budget for premiums to be around this level for a little while yet...Brian Boehmer
But Mr Boehmer said whilst the Fos increase "focused the minds" of underwriters, it was not behind the premium increases and drop in the number of insurers willing to write the class.
He said: "The increases in premiums being put forward is largely down to the claims activity that these insurers are seeing.
"You’re adding to some difficulties in the insurance market...and there’s a restriction in insurer’s appetite with an increase of rates even for practices with no claims activity."
In its annual review published last month the financial ombudsman reported it had received 1,915 new complaints about advisers in the 2018/19 financial year, jumping 14 per cent on the 1,678 received in 2017/18.
In a performance management review last year Lloyd's of London ranked non-US professional indemnity insurance as the second worst performing class in 2018.
Mr Boehmer said: "Advisers should budget for premiums to be around this level for a little while yet. But there needs to be a period of benign claims activity before rates will reduce, and at the moment we’re just seeing more and more claims."
Julian Brincat, director of IFA at broker Protean Risk, disagreed somewhat.
He said he had seen a "noticeable shortage" of insurers participating in the IFA PI market but he does not believe current claims activity was directly correlated to the increased rates and excesses that many firms are now facing.
He said: "One of the difficulties that underwriters are facing is how to assess the exposure that IFAs have as changing regulation and Fos decisions have the potential to create large systemic losses in the market.