U-Boat victories and claims

[Adriano Baumgartner]

Good night to all on board!
I was making some researches and found a RAF pilot who claimed 3 U-Boat victories ( actually none of the U-Boats he claimed in 1940 were sunk ) and got the credits for sinking them.
I would like to know, HOW the RAF or USAAF credited their aircrew members with this kind of "victory"?
We all know that by late 1942 the Intelligence Services of both countries were able to "read" Kriegsmarine´s ( ULTRA, Enigma deciphering, etc...) reports. Did they "cross-check" the aircrew claims versus the losses reports at that time?
BUT early in 1940, 1941 - did the RAF credited those "destructions" to the pilot´s report of combat only? I mean: "saw bubbles and foam...and patches of oil..."?
I also communicated with former Mosquito airmen who fought and sunk merchant ships. One of them told me they were credited to the Squadron as a whole, not to indidividuals..Of course, on the heat of Battle, each Mosquito carying 8 rockets, it was impossible to determine who sunk what...
ANY comments or information about U-Boat being credited to RAF and USAAF airmen?
Many thanks in advance for any answer and help.
Adriano