How long the UK transit VISA is valid ?

[rajiv_ksharma]

I will be travelling to India via UK. Me and wife will be using the Advance Parole to enter the US. I dont have a valid visa anymore(completed 6 years) . I will be getting the UK transit visa (DAT) . Does anybody know how long this visa is valid for ,I mean in terms or days or months ? Cause my wife will have a open return ticket and may stay 2-3 month in india. Anybody let me know.
Thanks.
Rajiv.

 

[Shapath]

We had to take a transit visa for UK as well back in May 2004 and I believe it was given for 3months. I will update this thread if it was different.