WW2 U.T.P (Upper Thames Patrol) cap badge, silver plated ?

Unusual badge being a standard brass UTP that has been period era silver or nickel plated. This was obviously done for senior officer  or a simple enhancement, due to the wear they obviously got away with wearing it for a long time.

The Upper Thames Patrol (UTP) was a volunteer Home Guard unit formed in 1939 to secure the non-tidal River Thames from Teddington to Lechlade during World War II.
It patrolled the river 24 hours a day using private launches and foot patrols to protect locks, weirs, and bridges from invaders, saboteurs, and enemy signaling, while also aiding blackout enforcement and bridge demolition readiness.
At its peak, the UTP had nearly 6,000 members, including women, who committed unpaid hours weekly until disbanding in late 1944.