Source: Leicestershire War Memorials Project.
Thomas Gaufrey Wearmouth Appleby was co-pilot of Wellington 1A N2904, which took off at 09:40hrs with 6 other no. 37 Squadron Wellingtons from RAF Feltwell, on the 18th December 1939. Their mission was to target any enemy battleships or cruisers present.

Having rendezvous at 10:30 hrs over Yarmouth, the Wellingtons flew in a diamond formation with 9 other aircraft from No 149 and No 9 Squadrons. The formation was attacked south of Wilhelmshaven at 12:30 hrs by approx. 30/40 enemy aircraft and upon reaching the harbour, they encountered heavy AA fire from both shore-based batteries and Navel craft.
Aircraft N2904 was shot down by the pilot of a German fighter. The bomber lost control and crashed into the sea off Wilhelmshaven. All six crew members were killed.

No suitable enemy battleships or cruisers were seen during the mission. After leaving the area, the aircraft were followed for 70/80 miles to the German coast by the enemy fighters. A total of 12 aircraft were shot down on this operation. Situated on the island of Wangerooge, the Germans had been tracking the bomber force for many miles using the experimentlal early warning Freya radar system.

The total loss for No 37 Squadron from this operation: 21 killed, 1 injured (died from injuries), 4 prisoners of war. Only one aircraft of the Squadron returned to base.

The tragic events of December 18th 1939, were later termed the Battle of Heligoland Bight - first named air battle of WW2. It was a baptism of fire for the RAF, with the loss of 57 airmen and 12 Wellington Bombers. As a result of this disastrous air raid, the tactics of Bomber Command changed to night time operations only and informed RAF tactics for the rest of the War.

Thomas GW Appleby, son of John Stanley and Norah Appleby, was granted a short service commission as Acting Pilot Officer on 14/07/1934, and his P/O rank was confirmed 14/07/1935. He was promoted to Flying Officer on 14th April 1937, and attained the rank of Flying Lieutenant on the 14th April 1939. On the 8th May 1939, F/Lt Appleby assumed command of A flight No. 27 Squadron.

The crew of N2904 on 18/12/1939 were:
Capt. Sqr/Ldr Ian Victor Hue-Williams 29219 (missing)
Pilot F/Lt Thomas Gaufrey Wearmouth Appleby 34227 (missing)
Nav. F/O Arthur Richard Vaughan Williams 33293, age 23 (killed)
Obs. Sgt. Alister Raymond Norris 580831, age 23 (missing)
W/Op/Air/Gnr. LAC John Arundel Barstow 550716 (missing)
Air/Gnr. LAC Ernest Lowe 540706, age 21 (missing)

Thomas G W Appleby is also commemorated on the Runnymeade Memorial, Surrey, Panel 1, and on the Little Grandsen Roll of Honour.

https://www.heligoland39.org/
http://aircrewremembered.com/hue-williams-ian.html