McNamara took part in both Norwegian campaigns while serving in 263 Squadron.

At 12:00 on 25 April 1940 Pilot Officer McNamara (Gladiator N5579) led a section of Gladiators, which intercepted an early afternoon attack by twelve He 111s from II./LG 1 and six Ju 88s from III./LG l. McNamara led the section in a deflection pass on a 4./LG 1 Heinkel flown by Unteroffizier Helmut Nolte, which force-landed near Lesjaskog in full view of everyone on the ground. One member of the crew was killed and three of them taken POWs.

Believed to be the He 111 shot down by McNamara on 25 April 1940.

263 Squadron suffered heavily losses and was soon withdrawn back to Great Britain to be re-equipped.

On 21 May the squadron again landed in Norway. This time at Bardufoss in northern Norway after having flown off from the carrier HMS Furious.

Flight Lieutenant Mills was decorated with the DFC on 10 May 1940 and the citation stated:

Pilot Officer Sidney Robert McNAMARA(41599)
“This officer led a successful attack on an enemy Heinkel III aircraft and showed great determination and courage in pressing his attacks. After landing from this engagement he also displayed bravery during an enemy bombing attack by remaining in his cockpit to start his engine and taking off under machine gun fire.”

On 14 May, 263 Squadron again sailed for Norway aboard the carrier HMS Furious.

McNamara took part in the successful evacuation of fighters from Narvik on 8 June 1940 when he and nine other pilots from 263 Squadron landed their Gladiators aboard HMS Glorious. However, this successful evacuation was avail when the carrier was sunk by the German battlecruisers Scharnhorst and Gneisenau later in the day with the loss of almost all aboard, Donaldson being one of them.

At the time of his death McNamara was credited with 1 biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1940
1	25/04/40	12:00-	1	He 111 (a)	Destroyed	Gladiator II	N5579	Lake Lesjaskog	263 Squadron

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) He 111 of 4./LG 1 flown by Unteroffizier Helmut Nolte shot down. Crashed near Lake Lesjaskog around 12:00. One member of the crew killed and three POWs.

Sources:
Fledgling Eagles - Christopher Shores with John Foreman, Christian-Jaques Ehrengardt, Heinrich Weiss and Bj rn Olsen, 1991 Grub Street, London, ISBN 0-948817-42-9
Gloster Gladiator Home Page - Alexander Crawford
The Commonwealth War Graves Commission
The Gazette