A three-member panel appointed by the Association of London Government is preparing a draft report that will be presented by the end of the month, in time to influence council budgets for next year.
Chaired by Local Government Commission chairman Malcolm Grant, the panel includes Rodney Brooke, former secretary of the Association of Metropolitan Authorities, and Bridget Rosewell, adviser to the Treasury on monetary policy.
Several boroughs have already commissioned independent reviews and have either changed their allowances systems or are considering it.
Mr Widdicombe's recommendations to increase Camden leader Richard Arthur and Hammersmith and Fulham mayor Andrew Slaughter's pay to as much as£40,000 were substantially reduced by members in both councils.
While it is widely agreed that salary-level allowances would open councils to a wider range of candidates, they remain politically sensitive.
Richmond upon Thames LBC corporate services manager John Bennett, support officer for the panel, said the first report would set out a common approach for an allowances framework rather than councils all doing their own work.
'No one has used the word salaries,' he said, but the thrust of recommendations would be in line with earlier reviews supporting higher remuneration for members doing responsible, time-intensive jobs.
A second report from the panel will look at carers' allowances, tax and pensions.
The ALG wants a compact between boroughs where they would agree to a common model, with some local changes.
The ALG last year surveyed all 33 London boroughs on changes to their political arrangements and allowances, in light of government legislation that will introduce elected executive members and in some councils mayors.