The Upper Thames Patrol was part of the Home Guard. My late father-in-law was a member and I have his old badge. During WW2, he was a skilled worker in the Miles Aircraft factory and Woodley flying school and worked in the UTP when off duty.
As far as I can tell they patrolled the river mainly to inspect the bridges for sabotage but also to report anything untoward e.g. parachutes in the river and incendiaries etc. and to check out every pub for subversives and beer quality!
The HQ of his group was at the Roebuck Inn near to Tilehurst. The joke was that U.T.P. stood for "Upstream To Pub".
I would be interested to contact anyone else with connections to this group or information pertaining to the Roebuck patrol.