Believed to be

No. 1202558, Sergeant (Air Gunner), Peter Norman LISTER
Aged 21
medals unknown
No 11 Operational Training Unit, Royal Air Force Volunteer Reserve
Died on Active Service on Monday 15th December, 1941

The only Peter Lister on CWGC list is buried near Nottingham, but so far no connection found with Exning or Newmarket.
He was born in Nottingham on 4th June 1920 ( Nottingham Q3-1920 , to Herbert Norman and Agnes Jane LISTER (née HOBBS) of 102 Leslie Road, Nottingham.

In the 1939 register, at 31 Bingham Road, Nottingham were Peter Norman LISTER [4-7-1920] a draper's assistant; his father Herbert Norman LISTER [1-12-1878] a retired wholesale draper and his mother Agnes June {12-1-1885]. None of which explains any connection with Exning.

Source: AWM 237 (65 NAA : A705 163/146/91 Commonwealth War Graves records. W R Chorley : RAF Bomber Command Losses Operational Training Units, Page89, Volume 7.

Aircraft Type: Wellington Serial number: X 3170 Radio call sign:unknown. Unit: ATTD 11 O.T.U. RAF Summary:
Vickers Wellington 1C- X3170 (W1156) took off from RAF Bassingbourn on the night of 15th December 1941, to carry out a night cross-country training exercise. While descending at speed, the aircraft flew into the ground at approx 2300 hours on Whittlesey Mere, some 5 miles SSE of Peterborough in Northhamptonshire. The aircraft disintegrated on impact and all the crew were killed (Peter would have been the tail gunner). They were:
RNZAF Sgt A L Sanderson, Captain (Pilot).....RNZAF Sgt D J Dempsey, (Pilot) ....... RCAF Sgt H B L Gittins, (Observer)....RAF Sgt B L Grove-Palmer, (Wireless Air Gunner).....RAAF 404636 Sgt W R Myles, (Wireless Air Gunner)...RAF Sgt P N Lister, (Air Gunner)
Five of the crew are buried in the Bassingbourn cum Kneesworth Cemetery, UK., Sgt Lister is buried in the Arnold Cemetery, Nottingham.

Peter is buried in Arnold Cemetery, Redhill, Nottingham..Ref: class B. un consec. grave 2655

click here to go to the Commonwealth War Graves Commission website for full cemetery/memorial details