Fears Colliers Wood will be lumbered with little more than a massive pile of rubble and a giant building site indefinitely are mounting with developers of the Brown and Root Tower unable to set out a time scale for refurbishment.

The wrecking ball was taken to the car park next to the tower - voted London’s ugliest - two weeks ago, marking a start of work on the derelict 17-storey monolith.

But activists are concerned this could be a false dawn with final planning agreement on details of the refurbishment yet to be reached, even though developers Criterion have said full refurbishment of the tower was anticipated to start within four months.

Colliers Wood councillor, Nick Draper, said: “If this project genuinely goes ahead without delay, that’s great, but I’ll believe it when I see it.

“It’s great they have started but it wouldn’t be a surprise if full construction is still some way off. If all they do is replace a car park, that’s no good at all. Colliers Wood needs ongoing action and can’t be left with a building site indefinitely.”

Keith Spears, founder of community group Making Colliers Wood Happy, added: “Most residents are relieved the car park is at last being demolished having been left empty and unused and falling into a state of disrepair over the past five years.

“There were a group of illegal immigrants living in there in a state of squalor since January. However, there is a concern that what we might be left with is a pile of rubble and more hoardings, because developers want to increase the number of residential units on the site.”

Developers Criterion were unavailable for comment but last week said development on the tower was expected to commence within four months, although a completion time was yet to be determined.

A BBC poll saw the tower voted the ugliest building in London in 2006, but plans to demolish it have been widely considered unviable as it sits directly above the Northern line and would have to be pulled down piece by piece.