LONDON-Chicago-based broker Aon Corp. is quickly bringing its acquired London operations under the Aon corporate banner.

The businesses of Nicholson Jenner Leslie Ltd., Bain Hogg International Ltd. and Alexander Howden Group Ltd. will be merged by July 1 to create Aon Group Ltd.

Wholesale, reinsurance and specialist divisions of the three brokers will be consolidated under the Aon name, though how Minet Ltd., Aon's most recent acquisition, will be integrated remains to be seen.

The U.K. retail operations of Bain Hogg Group P.L.C. and Alexander & Alexander Ltd. are expected to be combined into Aon Risk Services later in the year.

And the actuarial and pension consulting operations, Alexander Clay and Godwins Ltd., are being combined to form Aon Consulting Ltd.

After Aon Group Ltd. announced the new structure and board last month, the broker last week internally announced the appointment of 150 managing directors and directors in London.

Aon's London board is headed by Alan Colls, as chairman, supported by Dennis Mahoney as deputy chairman and chief executive. Mr. Mahoney is also chairman of the executive committee. Francis Marjoribanks is Aon Group's chief financial officer and also sits on the executive committee.

Other board members are: David Ambrose, Colin Bryan, Charles Cantlay, Paul Chilton, Alan Griffin, John Kavanaugh, Ross McKenzie, Paul Milton, Bill Oram, Jonathan Palmer Brown, Tony Pickering, Anthony Pinsent, Brian Stewart-Brown, John Turner and Alan Williams. John Hill is company secretary.

Already, Aon Group Ltd. has split into nine brokerage divisions: aviation direct, headed by Mr. Palmer Brown; aviation reinsurance, and marine and energy reinsurance, both headed by Mr. Stewart-Brown; marine and energy direct, headed by Mr. Chilton; non-marine reinsurance, and non-marine direct, headed by Mr. McKenzie; financial institutions and professional risks, and special risks, headed by Mr. Kavanaugh; and overseas partner offices, headed by Mr. Williams.

But the physical process of bringing the brokering teams from the various constituent companies together is still to happen, and until July 1-when Aon Group will be fully registered as a company under British law, and registered as an insurance broker with both Lloyd's of London and the Insurance Brokers Registration Committee-brokers are working under their original company names.

A spokesman for Aon said there was no information about the level of staffing expected at Aon Group. However, he did comment that Aon Group is aiming for a "flat structure for management efficiency."

Back-office operations also will be combined from the beginning of July, leading to the closure of Bain Hogg's administrative office in Haywards Heath in the south of England. Staff will have the opportunity to move to Romford in east London, which currently services Alexander Howden's business and will process Aon Group business. Or they can move to Glasgow in Scotland, where the retail business will be processed. About 400 jobs are expected to be trimmed from the back-office restructuring.

Consolidation activity within the Aon-owned London operations has been driven by an integration task force, with the help of management consultants. "The whole logic for the integration was to get on with it," said the Aon spokesman, referring to the speed with which it has progressed.

Overall, the organization now has a number of properties on its books. Aon Group will be housed in the current Alexander Howden building in Devonshire Square, while the risk services operation is expected to move to Bain Hogg's present headquarters, Lloyd's Chambers to the east of the financial district.

Bringing these new businesses under the Aon banner likely will change the worldwide corporate structure, though Aon is yet to decide how.

"We are now in growth mode," said the Aon spokesman. "There is new business to win and new opportunities."