Colinloves - I am assuming you know this story already:
https://en.wikipedia.org/wiki/HMS_Conway_(school_ship)
https://menaibridges.co.uk/history/l...rea/hms-conwy/
http://hmsconway.org/
The information only gives a broad potential timeline unfortunately. Those who have crossed the Menai straits will know the 'swellies' are very powerful at certain states of the tide. They have to be treated with great respect. Conger eels in adjacent bridge structure are monsters! Not a place where you would want a vessel to run into difficulty.
It will be interesting to see if a button expert can assist.
Mike