P/O Johnnie L. Allen flew with No 54 Squadron from the outbreak of the war.

Pilot Officer Allen made the squadron's first claim of the war when he shot down a Ju88 in the Dunkirk area on 21st of May.
On the 23rd of May 1940, he took part in a daring rescue operation. He and A.Deere escorted their Flight Commander, James Leathart, to France where he was to land a Miles Master trainer and pick up the C/O of No 74 Squadron who had made a forced landing on the airfield at Calais-Marck.
The pick-up was made, with Allen watching from 8,000 feet and Deere circling at low level. An approaching formation of Bf 109's was spotted by Allen as the Master taxied out for take-off. As a strafing Bf 109 pulled out of its dive, presenting a perfect target, Deere fired a short burst and the aircraft stalled and then crashed into the sea. Deere, climbing to help Allen, crossed the path of two Bf 109's, one of which turned towards him. Deere also turned, firing at the second one, which rolled over and dived away. Pursuing the first one, he caught up at treetop height and pursued him, firing off his remaining ammunition before the German headed for home. Diving towards the coast Deere called up Allen and was relieved to hear him answer. In the meantime the Master had taken off and headed for Hornchurch. In the action three Bf 109's had been shot down and three others severely damaged with no losses.

P/O J. L. Allen was killed on the 24th of July 1940 near Margate. He was 24 years old.
His Spitfire (P9549) or (R6812) was shot down on convoy patrol by Bf 109's of III Gruppe of JG 26. He attempted to reach Manston after his Spitfire had suffered engine damage, but the aircraft stalled and crashed at Cliftonville at 12:30hrs.
He was buried with full military honours at Margate Cemetery, Kent.