[5] In 2019, it was proposed to deliver the project as part of a wider Clyde Metro network, using a new light rail line via Govan.

The most controversial proposal in the scheme was the building of the line on a viaduct over playing fields in the Paisley St. James area and into Glasgow Airport.

[8] After much discussion, SPT assured local residents that the playing fields would be returned to original use, with even better facilities such as under-soil drainage and new changing rooms.

In December 2008, Transport Scotland announced that the tender competition will begin in spring 2009, meaning GARL would have been operational in early 2013.

Subsequently, on 11 July 2008, Transport Scotland announced that 38 Class 380 trains have been ordered for use on Ayrshire and Inverclyde services and also the Glasgow Airport Rail Link.

[10] On 17 September 2009, the Scottish Government cancelled the airport branch component of the GARL project amid concerns over the need for public spending cuts.

[11] However, elements of the GARL plans that upgraded the Glasgow–Paisley lines (including replacement of life-expired signalling, provision of two additional platform at Glasgow Central, and installation of the additional tracks between Shields and Wallneuk Junction) were excluded from the cancellation decision and instead taken forward as the separate Paisley Corridor Improvements project, which was completed in 2012.

[15] On 3 July 2014, an article in Glasgow's Evening Times newspaper - jointly written by Prime Minister David Cameron and Chief Secretary to the Treasury Danny Alexander - said: "Glasgow plans to create a £1.1 billion infrastructure fund that will support projects such as the city centre-airport rail link, major improvements to the region's roads and bus network, and the development of new employment sites.

A new proposal was then suggested to adopt the cheaper Personal Rapid Transit system instead between Glasgow Airport and Paisley Gilmour Street.

[6] Glasgow MP Paul Sweeney criticised Glasgow City Council leader Susan Aitken for supporting the downgraded option to use the people mover system to the airport, instead of light rail that would be integrated with the main Paisley Gilmour Street railway station and the wider city region rail network.