Its a Knockout mixed with Allo Allo it has to be Schoolditz by Frank McDiarmid in the School Fun Holiday Special!!
Heres the first one from number 1 School Fun 15th October 1983..
Frank obviously enjoyed drawing this strip with lots of German..war references..
like Schoolditz on the castle is a play on the word Colditz..
This strip was around due to the success of the comedy 'Allo Allo!' http://en.wikipedia.org/wiki/'Allo_'Allo!