More than a decade after the abolition of the Greater London Council, the system is 'both complex and politically weak' says the report, London government: options for change.
Research by Tony Travers and George Jones of the London School of Economics says the present arrangements must 'inevitably' be reformed within a few years.
However, the attitude of the London boroughs themselves could create obstacles to change. The report says: 'Individual boroughs have become involved in London-wide initiatives, some borough leaders have assumed a visible role in London-wide politics.
'Boroughs might object to any proposal to transfer control over, say, planning advice, research, or parking regulation to a mayor or London-wide elected authority with a separate electoral mandate.'
Nevertheless, the report says: 'Given its complex and often unaccountable nature the system of London government works surprisingly well.'
It concludes: 'Reform of London will never be easy. Too many organisations have a view about what is best for them and for the city.
'The boroughs remain powerful political entities. But a mayor and a London-wide authority are favoured by the majority of Londoners.
'It is difficult to see why, in a democracy, people should be forever denied the political institutions they want.'
The Labour Party last week launched its Manifesto for London with pledges to appoint a mayor and a strategic authority for the city if a referendum shows that is what residents want.
The manifesto also promised:
-- A new public/private partnership to improve the Underground
-- The release of capital receipts to be invested in building new houses and refurbishing old ones
-- The formulation of an investment and business strategy for London
-- A moratorium on all hospital closures
-- A London-wide air pollution strategy.