Friends

I am working on 2 year Work Permit in Canada. Workpermit and my multiple entry temporary resident visa is valid till Sept. 2009. I want to make a trip to India in March via UK and will come back in the same month. Please advice that do I need a transit visa for transit in London (UK).

Thanks

If you have a stamped valid US/Canada visa, you don't need a transit visa for UK.

How long you will be in UK ?

I will be in UK (airport) only for the time that is required to board the connecting flight.

If you are not transferring to LHR to Gatwick and you have your onboard flight Ticket (Boading pass) and the gap is not more than 24hrs. You don't need a Transit visa.
You can search in Charcha there is a discussion about 'Visa' for London....

A transit passenger is not required to hold a transit visa if he holds or a person with whom he arrives in the United Kingdom holds on his behalf:

1) A valid visa for entry to Australia, Canada, New Zealand or the United States of America and a valid airline ticket for travel via the United Kingdom as part of a journey from another country or territory to the country in respect of which the visa is held;

http://www.ukvisas.gov.uk/en/doineedvisa/visadatvnationals