I wonder if anyone here can help with something my Father saw as a child during the last War?

In 1944, he was just eleven years old.
My Grandfather moved around the Country a fair bit due to his various postings (906 Squadron at RAF Stanmore and RAF Marston Moor with Group Captain Leonard Cheshire).
However, during that year, he remembers seeing a Lancaster with all the fans turning, fly slowly over Great Missenden in Buckinghamshire at just 300 feet.
He said that is was dumping fuel from its starboard wing and alone. He had the impression that it was late back from a raid and damaged.
Dad has always wondered what happened to the crew and whether they got back safely?

He knows that I read this forum and I volunteered to put something up here for him – just in case...

The only clues that I have is the following:

1. It was during his summer holidays in 1944.
2. The Lancaster was travelling from the Amersham direction and over Great Missenden – very low. Dad reckons it was just 300 feet. (He later became a pilot and so I guess his estimate is reasonably accurate).
3. It was dumping fuel.
4. All fans were turning.
5. It was a clear blue summers day. (The weather might narrow it down during August).
6. It banked slightly to port when over Missenden and followed the Rignall Farm Road, which takes it roughly over Chequers and in the direction of RAF Westcott.

It left a lasting impression on my Dad and always hoped the crew got home safely.
It would be amazing if anyone could help with this.

He also remembers the tragic collision of two Wellingtons over Prestwood nearby, and a Halifax full of Deer carcasses fly into a hill opposite where they lived near to St Peter and St Pauls Church at Gt Missenden.
Another memory he has is of a Doodlebug that lit up his bedroom one night, and with an intermittent (faulty) power unit. It frightened him so much with its roar that he dived under the bed! It eventually crashed into woods out near Dorton House (Brill). I’ve actually seen its enormous crater and shrapnel still line the sides. Hope this is of interest.