Department store group Fenwick is to enlarge its flagship store on London’s Bond Street by about 14,000 sq ft.

The iconic five-floor department store will expand into the space next door, left by the demolition of the Apollo House office block.

The building project is expected to last for more than 18 months, with the first new departments completed by autumn next year and with full completion by spring 2010.

A Fenwick spokeswoman said that details of the in-store space allocation and design have yet to be finalised, but it is expected that each of the store’s departments would all get additional retail space.

The extension of Fenwick, which straddles the junction of Bond Street and Brook Street, will also include further office space for the retailer, on its fourth floor.

Fenwick is also refurbishing the fashion floor of its branch at Brent Cross shopping centre, where it has been an anchor tenant since the scheme opened. In September, Fenwick unveiled a revamped menswear department at its 225,000 sq ft Newcastle store.

Retail Knowledge Bank senior partner Robert Clark said: “On the assumption that it [the building work] is not going to be finished until the economic cycle improves, Fenwick should be in a position to drive some good bargains on construction costs.”

Fenwick has 11 stores, including two, in Kingston and Bracknell, that trade as Bentalls. The group bought its 11th store in March this year, the Colchester department store Williams & Griffin.

For the year to January 26, the family owned retailer delivered group sales up to£280.3 million, compared with£273.6 million the previous year. Pre-tax profits rose 7.2 per cent to£35.9 million. Operating margins remained strong, despite a 0.1 per cent fall to 10.7 per cent. Gross margins rose 1 percentage point to 42.1 per cent.