According to the BBC, Network Rail has given "approval" to the proposed privately funded Windsor Link Railway which has aspirations to link the Southern and Western lines to Windsor by means of a tunnel under the Thames. This would allow a Staines-Slough service, presumably by extension of the Waterloo-Windsor services.
Further details here:
http://www.bbc.co.uk/news/uk-england-berkshire-22983453
http://windsorlink.co.uk/
http://www.sloughobserver.co.uk/new...90502-boost-for-windsor-link-railway-project/
David
Further details here:
http://www.bbc.co.uk/news/uk-england-berkshire-22983453
http://windsorlink.co.uk/
http://www.sloughobserver.co.uk/new...90502-boost-for-windsor-link-railway-project/
David