Pro-independence Scottish political parties—the Scottish National Party (SNP), Scottish Green Party, Scottish Socialist Party (SSP) and Solidarity—are opposed to the basing of the Trident system close to Glasgow, Scotland's largest city. Some members and ex-members of those parties, such as Tommy Sheridan and Lloyd Quinan, have taken part in blockades of the base. In the House of Commons vote in 2007, the majority of Scottish members of parliament (MPs) voted against upgrading the system, while a substantial majority of English, Welsh and Northern Irish MPs voted in favour.