The line, as proposed by BAA, would run from Heathrow Terminal 5 across the suburbs of southwest London to Waterloo, with additional direct rail services from the airport to Reading and Guildford.

[3] Various alternate forms have since been proposed, including a revised plan Airtrack-Lite put forward by Wandsworth London Borough Council in 2011.

The reason cited was that "the Government has confirmed that its most urgent priority is to tackle the UK's budget deficit and that there will be a spending review in the Autumn.

[9] In the event, Airtrack was not mentioned in the spending review and, as a result, in November 2010 BAA announced that the "public inquiry remains deferred".

The group commissioned consultants to study the economic benefits of the scheme funded by the (now defunct) South East England Regional Assembly.

[17] Surrey County Council, although it had previously objected, revised its position after BAA offered to fund £11 million of transport improvements.

[22] In response to these concerns, BAA published assurances in their consultation literature that the Feltham depot would have been designed to limit noise and light pollution, and with landscape screening.

Opponents have expressed concerns about the impact of the scheme on these crossings, and local campaigners have that claimed more frequent trains would increase waiting times at closed barriers and cause more road congestion.

[27] Wokingham Borough Council objected to BAA's plans on the grounds that no proper impact assessment had been carried out on level crossing dwell times.

The proposed line would use a west-facing connection near Slough, which would allow through trains to serve the airport from South Wales and Bristol if a business case could be established.