Wave Glider USV in USN service?

[Grey Havoc]

From last October:

Mystery Deepens Around Unmanned Spy Boat Washed Up In Scotland (Updated)

The unmanned vessel washed up in Scotland last week does not belong to the Royal Navy. But it may have been on an intelligence-gathering mission for someone else, along with a second craft found last year.

www.forbes.com

Unmanned 'spy vessel' washes up in Scotland

This unmanned surface vessel isn't British but it is, apparently, being operated in British waters.

ukdefencejournal.org.uk