There is now an amended Forum Bar to extradition, introduced by the Crime and Courts Act Schedule 20 Extradition
In theory this gives Judges the discretion to apply common sense and to determine if it would be in the interests of justice to hear a dual jurisdiction case in the UK or in a foreign court, something which the Extradition Act 2003 prevents them from doing.
It is hard to say whether or not this would have made any difference, if this had been in place in 2002 when Gary McKinnon was arrested or subsequently in 2003 when the ex post facto Extradition Act 2003 was applied to his case retrospectively, there is still too much scope for secret backroom deals between foreign prosecutors and the technologically inept and under resourced Crown Prosecution Service.
N.B. Although section 50 which simply calls the above Schedule 20, is on the Statute Book, it is not yet in force until it is Commenced by Order.