Gray was 25 years old, and a sergeant in 12 Squadron, Royal Air Force during the Second World War when the following deed took place for which he and his pilot Flying Officer Donald Garland were awarded the VC in a joint citation.

On 12 May 1940, over the Albert Canal, Belgium, one bridge in particular was being used by the invading German army, with protection from fighter aircraft, anti-aircraft and machine-guns. The RAF was ordered to demolish this vital bridge, and five Fairey Battle bombers were despatched with Sergeant Gray as the navigator in the plane leading the bombing attack. They met an inferno of anti-aircraft fire, but the mission was accomplished, much of the success being due to the coolness and resourcefulness of pilot Donald Garland of the leading aircraft and the navigation of Sergeant Gray. Only one aircraft made it back to base.

Gray is buried at the Heverlee War Cemetery near Leuven in Belgium.^[1]

The announcement and accompanying citation for Gray's VC was published in supplement to the London Gazette on 11 June 1940, reading:^[2]

Air Office, 11th June, 1940

The KING has been graciously pleased to confer the VICTORIA CROSS on the undermentioned officer and non-commissioned officer in recognition of most conspicuous bravery :-

Flying Officer Donald Edward Garland (40105)

563627 Sergeant Thomas Gray

Flying Officer Garland was the pilot and Sergeant Gray was the observer of the leading aircraft of a formation of five aircraft that attacked a bridge over the Albert Canal which had not been destroyed and was allowing the enemy to advance into Belgium. All the aircrews of the squadron concerned volunteered for the operation, and, after five crews had been selected by drawing lots, the attack was delivered at low altitude against this vital target. Orders were issued that this bridge was to be destroyed at all costs. As had been expected, exceptionally intense machine-gun and anti-aircraft fire were encountered. Moreover, the bridge area was heavily protected by enemy fighters. In spite of this, the formation successfully delivered a dive-bombing attack from the lowest practicable altitude. British fighters in the vicinity reported that the target was obscured by the bombs bursting on it and near it. Only one of the five aircraft concerned returned from this mission. The pilot of this aircraft reports that besides being subjected to extremely heavy anti-aircraft fire, through which they dived to attack the objective, our aircraft were also attacked by a large number of enemy fighters after they had released their bombs on the target. Much of the success of this vital operation must be attributed to the formation leader, Flying Officer Garland, and to the coolness and resource of Sergeant Gray, who in most difficult conditions navigated Flying Officer Garland's aircraft in such a manner that the whole formation was able successfully to attack the target in spite of subsequent heavy losses. Flying Officer Garland and Sergeant Gray did not return.^[3]

A Vickers VC-10 Serial 'XR807' of No. 101 Squadron was named 'Donald Garland VC & Thomas Gray VC'.

In 2005, to mark its 90th anniversary, No.12 Squadron RAF flew a Tornado GR4 with Flying Officer Garland's and Sergeant Gray's names painted under the cockpit as a mark of respect.

There is a monument on the bridge to the operation.

On the day of the attack on the bridge, Garland and his crew flew from the grass airfield near the village of Amifontaine, France, where No. 12 Squadron had been based since December 1939. No memorial to the airfield, and to the men who flew from it, has been reported to exist in the area.^[4]

• Flying Officer D.E. Garland & Sergeant T. Grey in The Art of War exhibition at the UK National Archives