I found exactly one hit for a lyric snippet from the first song the boys are singing in the mess, sung to the tune of "Lili Marleen" (http://videosift.com/video/Hanna-Schygulla-Lili-Marleen). I suppose it's dubbed "The Lancs of 75 [Squadron]".

The Lancs of Mepal, they're on their way,
Off to bomb the Jerries, they bomb them every day,
And when they wish to show their might,
They bomb the sods by day and night,
The Lancasters of Mepal, the Lancs of 75.

Off we go from Briefing and leap into our kite,
Open up the throttles and roar into the night,
We've left the flarepath far behind,
It's bloody dark but we don't mind,
The Lancasters of Mepal, the Lancs of 75.

There's the bloody searchlights waving round the sky,
Not much ruddy power and not too bloody high,
I hope they don't start shooting til we're through,
They might get me and they might get you,
The Lancasters of Mepal, the Lancs of 75.

Now we're through the target setting course for home,
Soon we'll see the Sandra's waving o'er the 'drome,
That's if we don't go off the track,
And stop a crafty burst of flak,
The Lancasters of Mepal, the lancs of 75.

Junkers off to starboard, Focke-Wulf off to port,
Gunner calls to Skipper, the range is getting short,
Prepare to corkscrew starboard, go,
We know our stuff and we're not slow,
The Lancasters of Mepal, the Lancs of 75.

Now we're in the circuit with a turn to land,
No intruders round us, ain't it bloody grand,
We fooled the Hun once more tonight,
Dropped a load right on the Reich,
The Lancasters of Mepal, the Lancs of 75.

When the war is over and there's no more ops to do,
We'll think of all our pals,
The ones who did not get through,
The pals who were with us through thick and thin,
That we one day the War would win,
The Lancasters of Mepal, the Lancs of 75.

http://www.ww2talk.com/forum/general/8985-wwii-dittys.html

Tags for this video have been changed from 'trumpet, WWII, enemy, sniper, D day' to 'trumpet, WWII, WW2, second world war, enemy, sniper, D day, lili marleen' - edited by calvados

^Quite right, Chic. Lili Marleen it is!

http://en.wikipedia.org/wiki/Lili_Marleen