Mr Middleton, selected from a short list of candidates, is to be introduced to the Lloyd's ruling council early next month and his appointment will be announced soon afterwards.
David Rowland, chairman of Sedgwick Group, the large insurance broking group, who has been nominated as the next chairman of Lloyd's by David Coleridge, the outgoing chairman, is expected to receive a salary package of pounds 400,000 or more if he gains office. At present the office of chairman of Lloyd's is unpaid, but following recommendations for a change in the way Lloyd's is managed the chairman's post will become a paid position from next year.
The combined salaries of more than pounds 600,000 will anger many members who are bearing the brunt of pounds 2bn worth of losses that have hit the market. Already, many have complained about the high level of salaries received by professionals in the market.
Before his departure as chief executive this summer Alan Lord, the former civil servant, was receiving pounds 200,000.
Mr Middleton beat two internal candidates at Lloyd's for the job: Andrew Duguid, head of market services, and Bob Hewes, head of regulation. Mr Middleton has played a role in plans by Midland Bank, Thomas Cook's parent, to sell Thomas Cook to LTU, the largest air-carrier in Germany and Westdeutsche Landesbank, the large German bank, for pounds 200m. As chief executive in the insurance market, Mr Middleton will sit on the ruling council of Lloyd's and work closely with a market board, designed to develop the insurance business.
Tomorrow, Lloyd's is expected to announce whether its council has secured a vote of confidence by the members following a month-long ballot.
Lloyd's has estimated that losses that will lead to insurance claims in Florida after the Hurricane Andrew damage will amount to dollars 1bn ( pounds 505m) in total for the insurance community.