Barnet Council's planning committee is expected to approve plans for 45 homes at 84 West Heath Road in Hampstead.

The controversial scheme, proposed by Highgate's Harrison Varma Projects (HVP), would see luxury housing built on a site previously used as a care home, and most recently as a home for part of Heathside School.

But neighbours have been upset by the scale of the development, argue it could cause traffic issues. They have commissioned reports questioning the financial contribution the developers are seeking to make to the affordable housing in the community.

Barnet planners are recommending the scheme is given the green light at a meeting on Thursday (July 29). However, the recommendations councillors will vote on include the proviso that if an appropriate agreement is not "progressed" by September 30, the town hall should then refuse the application.

The developer's contribution to affordable housing in the area became a point of contention, but in the council recommendation it makes clear that HVP has agreed to the Greater London Assembly's "hindsight review" process. This will assess the project should it be carried out to decide how much money should be contributed. In the Barnet report, this figure would be capped at £6.5m.

A number of different financial assessments of the scheme have been undertaken by surveyors on behalf of HVP, a group of neighbours, and the town hall itself – but differences in methodology mean each has arrived at a different figure.

In a report from firm BNP Paribas, on behalf of Crossier Properties, which is a firm where neighbour Sohail Sarbuland is a director, surveyors take issue with previous calculations of the "benchmark land value" arrived at by firms Gerald Eve and DS2.

The developer has proposed a minimum £900,000 contribution to affordable housing based on the report it commissioned BNP Paribas' calculations suggest "the scheme could support an additional contribution towards affordable housing".

It states a maximum contribution could be substantially higher.

But DS2's report says the project "cannot viably support" a payment in lieu of affordable housing at this stage.

In April the town hall deferred a decision on the scheme after residents held a protest.

The scheme's designers – Wolff Architects – describe it as "a high-quality, contemporary design" but neighbours like Beatrix Clark disagree.

She called it "hugely alarming", and a "monolith" that wasn't in-keeping with the local area.