It must be as there was only the one mast there (also a Unipole) and not a collection of them. Ironically Bushfiva did suggest this above.
I also had confirmation from Met Eirann it was not one of thier instruments, further indication that it must be related to the Coast Guard. The report in question also originates from them so I'm happy to say "Case closed"!
Thanks all for your help!
B314