64 had Hornet F.3s in 1949, based at Linton.
These folk may know more.
https://www.a-e-g.org.uk/under-the-bridge-fliers.html
Not the sort of event one would normally expect to see in the squadron authorisation book.
OTOH, close enough to be done within the timing of an ostensibly routine SCT sortie, or 'accidentally' as part of the apparent big air defence exercise the OP mentions.
The Scotsman 03 March 1949 -
https://www.britishnewspaperarchive....cotland&page=2
"Forth-Clyde area defence test air operations on big scale day and night attacks on docks and harbours"
LFH