Thank you for your enquiry regarding ML 263 which was part of the 17th ML Flotilla, comprising MLs 242, 256, 261, 263, 265, 266, 272 & 274. Naval History web site has some of the movements at various times for the motor launches in West Africa including this entry for 7 August, 1941
I have photos of ML 296 and 287, including general shots of life at Freetown, some of which may be found here.
If your relative is Petty Officer Motor Mechanic William Delaney, and if you have a photo of him, I could look through all the photos I have to see if he is in one of them. This is a group photo of some of the ML crews at Freetown which are more likely from boats in the 27th ML Flotilla.