Harrow West is a constituency[n 1][n 2] in Greater London created in 1945 and represented in the House of Commons of the UK Parliament.

Until 1997, it only returned Conservative MPs; since then, it has elected the Labour Co-operative MP Gareth Thomas on a fluctuating majority.

The area covers the largely Georgian conservation area on a stand-alone, partly park-lined hill which hosts the famous Harrow School; it also includes the urban Harrow town centre, as well as suburban streets of homes with good-sized gardens and well-kept small parklands.

The seat has fast London Underground links to the city centre and rail services, few dual carriageways and few high speed roads.

The western border district, town or neighbourhood of Pinner went to a new cross-Borough seat, Ruislip, Northwood and Pinner, making its source, based on a ward breakdown of the last result, and mirrored by local election results, a stronger seat for Labour; this was coupled with the inclusion of Marlborough ward which had returned many Labour councillors since World War II.