Hello Edward
Welcome to the forum, glad to have you onboard.
I don't have much information to give you unfortunately and suggest the best option would be to apply for a copy of your Grandfather's service details from the Ministry of Defence for which details are available in the
Service Records thread.
As far as Nigeria is concerned, given he was with Coastal Forces at that time too, then that would most likely be in connection with the Fairmile 'B' anti-submarine motor launches of Coastal Forces which operated out of Freetown, Sierra Leone in the main, and travelled north to Dakar and south along the Gold Coast to Lagos. You can gain some insight into the theatre of operations in West Africa through the photos and captions on our
Coastal Forces Flickr page.
Hope this helps
Regards
Admin