A seven-tower flat, hotel and retail development on Old Kent Road could pose a risk to the Bakerloo line extension if a tunnel boring machine “goes off on one,” Southwark Council’s planning committee heard.

Transport for London is considering extending the Tube line from Elephant and Castle into New Cross Gate via Old Kent Road.

The committee unanimously approved the development, where a hotel will sit on top of expected Tube tunnels.

But the use of piles during construction will mean there is no added pressure to TfL’s tunnels, the committee heard.

“We have actually taken the design of the basement of the hotel to a much more detailed stage than we normally would for this stage of the project,” Emma Pritchard-Selby, development manager for developer Strathclyde Pension Fund, explained.

“We’ve adjusted our piling methodology to allow TfL to build their tunnels after we’ve piled.

“The easiest way to describe it is [we will] pile either side of the tunnel with support in the middle so there is no pressure or load on TfL’s tunnels.

“The only real risk, and I say this is a very hypothetical risk, is that once TfL have agreed our piling methodology, which will be done at the stage where they know the design of their own tunnel…the only real risk is if the boring machine goes off on one and goes a bit far left,” she said.

TfL had made an objection to the development, which includes blocks between nine and 48 storeys for 724 flats, a supermarket, hotel, and cinema at the Southernwood Retail Park.

But it came to an agreement with the developer and the council that the hotel will not be built until the design and the paperwork of the extension had been finalised, and with written agreement from TfL and the council.

Further objections were heard from residents, Southwark Law Centre and the 35% Campaign, whose concerns included whether there was demand for a hotel, wind tunnelling and whether more affordable housing could be built.

The developer’s agent said there was demand for a four-star hotel, while the committee heard wind tunnelling would be mitigated from the planting of trees.

The committee also heard the land is not considered public land, meaning 35 per cent affordable housing was acceptable.

Of the flats, 148 will be let for social rent and 71 will be let at intermediate rent.

The developer will have to pay £16.7m towards the community infrastructure levy, £3m in s106 agreements and £750k for local employment and training initiatives.

The development does not comply with council policy around play space for children over 12, so £22,000 of s106 funding will go towards Southwark’s young adviser scheme, funding council staff for five months.

Lib Dem Cllr Damien O’Brien said there weren’t any grounds for refusing the application.

He said: “Although I am concerned with elements of this application, I am concerned we haven’t got anything concrete on which, for example, we would have to defend the decision for refusal at the inspectorate.

“While there are issues and thing we don't always like, I am minded to think it would be very difficult to refuse,” he said.

Because of the scale of the scheme it also needs to be approved by the Mayor of London.