All I could find was information on the 214 Sqn website which says:_
Flt/Lt Donald Howard AFM
Flt/Lt Donald Howard AFM, Navigator / Radio Operator, 2238475, Royal Air Force , Nationality : United Kingdom. KIA 11 September 1959 Age 31.
SEE CREWS AND LOSSES for Valiant B Mark I XD869 .
Date of Birth 11 May 1928 in Finsbury Park, London.
Stationed at RAF Marham.
He is buried in Marham Cemetery, Norfolk. RAF Grave 9.
Named on the following Memorials :
Armed Forces Memorial
Rolls of Honour, Church of St Clement Danes, London
Source : Jock Whitehouse and Armed Forces Memorial
This is probably already known to this officer's relatives