A planning application to build an underground tunnel from a £5m mansion, under the garden, to a swimming pool at the end of the lawn has been met with opposition from residents of Wimbledon Village.

The owners of 14 Marryat Road - the former home of London 2012 chief executive Paul, now Lord Deighton - are attempting to excavate almost their entire garden and build an enormous extension underneath.

Planning bosses will decide at Thursday's council meeting whether to give the plans, which include an underground gym, cinema, games room, sauna and adjoining glass tunnel leading to a proposed pavilion swimming pool, the go ahead.

The Parkside Residents Association say with basement conversions becoming increasingly popular, giving rise to so-called Iceberg Homes, Merton Council must keep up with the fashion and ensure there is a "robust supervision of the process".

Sue Cooke, chairwoman of the association, said: "This has been happening in Kensington and Chelsea for some time now, it is just suburban authorities have not seen it so much. We don't object to the principle of the basement under the garden, but if this is allowed without adequate supervision it will set a president to others."

"Most of these houses are more than 100 years old, construction could impact on neighbours houses. Generally the full impact of basement constructions are examined at planning stage, put it doesn't appear to have been done in this instance."

In March this year Kensington and Chelsea council proposed a limit to the extent basements can intrude into gardens, from 85 per cent to 50 per cent, and in October Westminster Council announced it was considering the same restrictions and also a basement tax which would mean an affordable housing contribution by the developer.

Famously, Chelsea owner Roman Abramovich was granted a planning permission to link three adjoining grade II-listed buildings in Cheyne Walk, Chelsea, through vast network of underground tunnels at a cost of £10m.

Marryat Road and Peek Road, among others in the Merton Conservation Area, were formerly owned by 19th century biscuit barons Peek Frean.

Peek, Frean and Co was established in 1857 in Bermondsey by James Peek and George Hender Frean, who started selling off plots around Marryat Road for people to develop at the turn of the 20th century.