Appleby was born in London in 1904.

It seems that he was a Boy entrant into the RAF between 1922 and 1924.

Sergeant Appleby took part in the revolt in Iraq in 1941 were he fought in the Fighter Flight at Habbaniya.

In June 1941 he was part of ‘X’ Flight, which had formed at Habbaniya on 6 June. This unit was equipped with Gloster Gladiators under the command of Flying Officer K. H. O. Young and had been formed to take part in Operation’Exporter’, which was an invasion in French-held Syria.

On 7 June the unit flew to Amman in Transjordan.

By 15 June ‘X’ Flight had begun making use of an advanced landing ground at Mafraq, to which six Gladiators flew each morning at daybreak for their scheduled patrol activity.
On this morning the six were all on patrol over Kissoué at 8000 feet when they entered the same airspace as a ‘patrouille double’ with Dewoitine D.520s from GC III/6, which had taken off at 08.30 to patrol over the Ezraa-Soueida area, led by Sous Lieutenant Pierre Le Gloan. At 09.30 three of the Gladiators were spotted below, Le Gloan leading Capitaine de Rivals-Mazeres and Sergeant Chef Mertzisen down in a dive on them, at once shooting down 35-year-old Flying Officer John Norman Craigie (RAF no. 43477) in Gladiator K7947, which crashed straight into the ground east of Ezraa, killing the pilot. A confusing engagement followed, during which Flying Officer Jeffrey and Sergeant Appleby each claimed a Dewoitine shot down.
Sergeant Chef Mertzisen’s No. 367 was badly hit and he came down in British-held territory at Sanamein but managed to return back home with the help of a Bedouin. Capitaine de Rivals-Mazeres claimed another Gladiator, which he claimed exploded on hitting the ground (he had probably also been firing on Craigie’s aircraft). Le Gloan attacked a second, claiming a probable, but then ran out of ammunition. His No. 277 was hit repeatedly, and he was pursued back towards Rayak by two Gladiators, crash-landing on the airfield with fighter in write-off condition.
A second patruille had meanwhile joined the fight, Sergeant Chef Elmlinger and Sergeant Mequet reporting a further victory between them, but incorrectly stating that the pilot had baled out. Either they or Le Gloan had hit Flying Officer Watson’s K7914, damaging it severely, causing him to fly directly to Amman.
The other four Gladiators landed safely at Mafraq.

He was promoted to Flying Officer on probation on 23 October 1942.

He was promoted to Flight Lieutenant (war subs.) on 23 October 1943.

Appleby ended the war with 1 biplane victory.

Claims:

Kill no.	Date	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1941
1	15/06/41	1	D.520 (a)	Destroyed	Gladiator		Kissoué area	’X’ Flight

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) Claimed in combat with D.520s from GC III/6. ‘X’ Flight claimed two victories for the loss of one Gladiator (Flying Officer J. N. Craigie killed) and a second damaged. GC III/6 claimed 3 Gladiators and 1 probable while losing two D.520 (Sergeant Chef Mertzisen in No. 367 and Sous Lieutenant Pierre Le Gloan in No. 277) without loss in life.

Sources:
Dust Clouds in the Middle East - Christopher Shores, 1996 Grub Street, London, ISBN 1-898697-37-X
Gloster Gladiator Home Page - Alexander Crawford.
The Commonwealth War Graves Commission
The London Gazette
Additional information kindly provided by Andy Ingham.