Copied from hounslowintransition:
Transition Brentford appears to be at slumber at present despite moves earlier this year by Cyrille to re-suscitate the group.
Syon Lane community allotment is still operating but Chiswick Transition too appears to be all quiet just now.
I have today renewed the hounslowintransition domain name just in case we or anyone in the London Borough of Hounslow manages to get a transition group up and running.
Please use the comment boxes (‘Leave a reply’) on this Hounslow in Transition website to get in touch or signal a local interest in the Transition Towns movement.
Trevor Bending.
Transition Brentford 
I would be interested to know whether the Brentford, Chiswick or Hounslow groups are still running
Thanks for this Colin. I think the short answer is no and probably the long answer too.
I was involved with Transition Brentford and maintained the website but I now live in Spain and I think the group has been inactive for some years. There never was a Hounslow group as such as far as I know but I set up a Hounslow in Transition website just in case!
I also believe Chiswick has been inactive for some time but I could be wrong.
Ealing Transition (who helped set up Brentford) are still growing (and going) strong and I think Transition Heathrow (‘Grow Heathrow’?) too.
I believe there may be a Southall Transition group perhaps associated with A Rocha and Minet Country Park in Hillingdon.
Syon Lane Community Garden (back of Syon Lane station) may still be active too?
Some of the people involved there and in Brentford went off to be ‘diggers’ – see diggers2012
That’s the long answer – you’ll have to google the rest!