Sgt. E. Lorne Vince and Sgt. F. L. Jason Grumbly were posted to 419 squadron in May of 1944. Vince had completed his gunnery training at No. 3 B&G at MacDonald Manitoba. Sgt. Grumbly had been trained at No.9 B&G at Mont Joli Quebec. They crewed up with 1st. Lt. Joe Hartshorn USAAF at No. 23 OTU at Pershire Worcestershire and then with him and the other members of the crew to No. 1664 CU (RCAF Caribou) at RAF Croft.

Hartshorn's crew:

Pilot 1st Lt. Joe Hartshorn
Navigator F/O C.E. T. Hamilton
Bomb Aimer F/O A.L. Delaney
WAG F/S W. D. Lydall
F/E Sgt. Ken Matthews RAF

Combat Report May 27th 1944 0217 hours

While they were outward bound and in the vicinity of the target Bourg Leopold, rear gunner Sgt.Vince observed a twin engine aircraft at a range of 400 yards on the starboard quarter up against the light sky.
The then unidentified aircraft was seen to bank and dive as though closing in for an attack. Sgt. Vince lost sight of the enemy aircraft below the horizon so he gave the corkscrew to starboard order. The aircraft he was protecting was KB716 VR-D, it completed one turn and then Vince gave the resume course command.
Just as the Lancaster levelled out the M/U gunner Sgt. Grumbly saw machine gun flashes on the port quarter down and saw the tracer pass over KB from port quarter to starboard bow. He then gave the corkscrew to port order at the same time he sighted the Ju88 breaking away from the port quarter and disappearing below. The enemy aircraft was not seen again and neither gunner had fired on the attacker.

Combat Report June7th 1944 0107 hours

While on route to the target Acheres rear gunner Sgt. Grumbly observed an enemy aircraft, an Me110 following VR-G at a range of 500 yards dead astern and slightly up, using the darkened sky behind it to hide in. The enemy aircraft closed in to 200 yards then Vince gave the corkscrew to starboard and opened fire at the same time. The Me110 followed KB733 through two of its evasive turns, then broke away to starboard without firing and then disappeared into the clouds.
Tracer was seen to enter the enemy aircraft by both Sgt. Vince and Sgt. Grumbly. A complete electrical failure in the Upper gun turret had kept Vince from firing on the enemy as well. The fighter was claimed as "Damaged"

Combat Report June 16th 1944 Multiple Attacks

While over the target at Sterkrale the Lancaster KB VR-G was attacked twice by unidentified enemy night fighters. It as first sighted by Sgt. Grumbly in the M/U turret at the starboard side quarter level. He gave the corkscrew to starboard order and just then flak burst at the aircraft's port wing with the fighter opening fire at the exact same time.
The fighter broke off on the starboard side beam and the crew lost sight of it.
Meanwhile Sgt. Vince in the rear gunner position had been searching the skies for any other attackers and saw an ME410 dead astern of his Lancaster. Opening fire with a long 400 round burst after giving the corkscrew order. The attacker stayed on the hunt for only 25 yards breaking of on the port quarter after Vince had started his defensive fire at 225 yards.
The long burst at such a short distance set the Me410's port engine on fire, but the M/U gunner Grumbly had spotted yet another unidentified aircraft on the port quarter, although this fighter did not attack.
Damage to the Lancaster was a hole punched through the M/U turret's rear area and the astrodome Perspex was knocked off. The cause of the damage , whether it was the fighter or flak was uncertain. But a claim of "Damaged" was made for the second fighter.