Thank you for your enquiry concerning your grandfather's service with MTBs 651 and 790. I took the liberty of rotating your image of the service record, added your later amendment to your original post, and then removed the duplicates.
MTB 651 served in the Mediterranean as part of the 33rd MTB Flotilla, then later the 60th MTB/MGB Flotilla, and the 61st MTB/MGB Flotilla, while MTB 790 served in Home Waters as part of the 72nd MTB Flotilla. I have quite a bit of information on MTB 651, and other boats in the flotilla which I will compile for you later. HMS Collingwood was basic training, Victory the main barracks at Portsmouth, HMS St Christopher the Coastal Forces Training Base at Fort William, with MTB 651 commissioning at the time, so your grandfather was with the boat from the start. St Angelo was Malta, Hornet the principal Coastal Forces base at Gosport, and Attack the Coastal Forces base at Portland.