Ealing Council has described the sale of the Filmworks cinema site as a "significant step" towards building a 1,000 seater cinema - but the move has cast doubt over the completion date.
Developers Land Securities this week announced the sale of the site to St George PLC after working with the council on the grand development since 2012.
The current scheme is set to have a mix of restaurants, cafés, shops and bars, 161 new homes and a landscaped public square.
The £100m development near Ealing Town Hall, connecting Walpole Park with Bond Street and Ealing Broadway, is also set to feature eight new screens as part of the cinema complex.
Labour Ealing Council leader Cllr Julian Bell said he has been given assurances by St George PLC that it will stick to these plans.
But he admitted the hoped completion date of 2018 set by Land Securities now hangs in the balance.
Cllr Bell said: "This brings us a significant step closer to the cinema’s return to Ealing.
"The Filmworks scheme is a fantastic opportunity to revitalise a large part of Ealing town centre to create a cultural quarter, more jobs and new homes.
"I am pleased that we will once again be working with Berkeley Group who are already playing a key part in transforming the borough with high quality developments such as Dickens Yard in Ealing and Southall Waterside.
"I've made it crystal clear the council and community want to see the cinema open as soon as possible and I'm confident St George understand this.
"It has taken some time to complete the deal between Land Securities and St George but it remains to be seen whether we have lost time or not."
'A sorry saga of delay after delay'
But Liberal Democrat Cllr Jon Ball said he feared the development, plagued by a string of delays, is set for another setback following the sale.
Cllr Jon Ball added: "Ealing residents demand that a new cinema is built as soon as possible, after this sorry saga of delay after delay.
"I have concerns about St George taking over the site. I will be seeking assurances that St George will be going ahead immediately to implement the Filmworks development that Land Securities planned."
A spokesperson for St George PLC said: "Whilst we would like to be able to confirm a start date, we have only just bought the site this week and are not in a position to do so yet.
"We hope that the local community will understand that we need to undertake a thorough review before we are in a position to do so.
"Rest assured, we are committed to delivering Filmworks and will be working hard to do so as soon as possible.
"The completion date, and the opening of the cinema, will of course be contingent on when we start and a smooth construction process.
"If we find that we need to make any changes to the planning permission, we will of course consult the local community, and would hope to make any amendments in tandem with delivering the development so we maintain momentum."
