Claridge’s plans to build a huge basement underneath their landmark London hotel with a swimming pool, a wine cellar and an in-house chocolatier.

Proposals filed with Westminster City Council reveal that the Maybourne Group plans to add five new basements under the Art Deco wing of the Grade II-listed building providing an additional 1,800 sqaure metres.

Permission was granted almost 10 years ago for a double storey basement to house some of its plant and maintenance facilities which are currently housed at the top of the hotel, where it is now preparing to build an extra two storeys of suites and guest bedrooms.

The group explained that the depth of foundations is the same whether it builds two basements or five, therefore, it has decided to proceed with the plans which allow the greater amount of space.

The new basement will create enough space for its in-house laundry, bakery and chocolatier as well as additional meeting rooms, dining area and changing rooms for staff.

The spa and swimming pool are described as a “must have” by the five star hotel, would be situated on the first basement level and include a mixed gender sauna, treatment and changing rooms.

The group argues that the extra space would also reduce the number of delivery vans coming to and from the hotel every day, thereby creating less noise and disturbance in the area.

Claridge’s carried out a consultation process earlier this year and met with residents and businesses in the area as well as stakeholder groups, English Heritage and the Greater London Authority (GLA).

The plans have now been submitted to the council and a decision is expected to be made within months by the planning committee.

Claridge’s is majority owned by the Qatar’s Constellation Hotels following its acquisition last year of a 64 % stake in the Maybourne Hotel Group, which also owns the Berkeley and the Connaught.

The owners said financing from additional shareholders has permitted the scheme to move forward through to construction and said the extension provided “the last opportunity” to create the space the hotel needed.

Architectural practice Blair Associates are acting on the project.