I think the messages may have been mixed up over time - he was certainly aircrew at start of war (Air gunner) but not by 31 July 1941 when he killed he was groundcrew (as confirmed by fact still LAC rank and role) but he was killed in a Motor Accident as stated below in newspaper
Leicester Evening Mail Sat August 2 1941
Killed on Duty
LA/C Thomas Frank Spiby RAFVR of Peating-road, Countesthorpe ,
has been killed in a motor accident while on duty.
Mr. Spiby, who was aged 29, leaves a wife
and one child. His mother is Mrs Neal of Medway-street, Leicester.
He was the grandson o the late Major T. Spiby of the Leicester
Joining the RAFVR at the outbreak of war, Mr. Spiby had taken
part in bombing raid over Norway as an air-gunner, but latterly
he had been on the ground staff. He was formerly employed by
Hannibal's of Willow-street, Leicester.
Additionally he was no where near Leicester when he was killed - I think they mixing up an aircraft accident local on same date ?
Deaths Sep 1941 (>99%)
Spiby Thomas F 29 Aldershot 2c 373 Scan available - click to view
Name: Thomas Frank Spiby
Rank: Leading Aircraftman
Death Age: 29
Birth Year: abt 1912
Death Date: 31 Jul 1941
Military Base: Bracknell, Berks
Service Number: 749041
Unit: Army Co-Op Cmnd Hq
Command: Army Co-Op Cmnd
Residence Place: Countesthorpe, Leicestershire
Burial Place: Welford Road Cemetery, Leicester