The seat is a mixture of urban and rural areas, with the population clustered in the south and hills, while glens and lochs dominate the landscape elsewhere.
Helensburgh is a middle-class seaside and commuter town, while towns in the Vale of Leven (such as Renton, Alexandria and Banhill) are all industrial in character. Dumbarton's principal industry was once shipbuilding - the Cutty Sark was built there - but now whisky bottling and blending are more important concerns.
Loch Lomond is being developed as one of the Scotlandís new national parks, under a Scottish Parliament initiative. A £60m development is also under construction at the neighbouring town of Balloch, to provide a visitors centre for the "national park", IMAX cinema and a retail park.
Labour has represented this seat in its various forms since 1936. The Conservatives were the second place party (with the exception of October 1974) until the 1997 General Election when the SNP overtook them.