P/O T. Kumiega reported for duty with 317 Squadron on 26th February 1941, when the squadron was based at Acklington.

On 18th December, the squadron was ordered to give cover to Bombers returning from attacks Brest. On arriving at patrol point, fifteen Halifaxes in groups of about four were sighted returning, one group of four being attacked by nine Me 109Fs. 317 Squadron immediately dived down to attack, and individual combats commenced at 12.45 hours simultaneously. Tadeusz swooped down on one enemy aircraft and had just opened fire with his cannons at 350 yards when he saw another Spitfire going after the same target, so he selected another Me 109F, gave a one-second burst, and saw smoke pouring out.
Tadeusz was then attacked by another Me 109F, evading it in slight turns and diving, following it down and getting in two more one second bursts, breaking away at 6,000 feet. The enemy aircraft continued in steepening dive, hit the water and sank five miles from French coast.

On 1st February 1942, (Flying Officer) Kumiega was posted to HQ 11 Group for a course of Advanced Tactical Training, and re-joined the squadron on 15th April.

On 26th April, while on operational sweep 'Circus 138', Tadeusz shot at a FW190 and follwed the enemy aircraft down when he just managed to evade violently two attacking FW190s which shot past him.

On 4th June, on 'Circus 186', the squadron had reached 26,000 feet when Tadeusz's engine stopped (as did the engines of F/O Koc and Solak) and they had to drop to 5000 feet before the engines restarted. No combat was made.