Lens, currently third in Ligue 1 of the French Championnat, fielded 10 players boasting first-team experience including ex-Liverpool defender Gregory Vignal.
They looked the part in the early stages with the impressive Jussie Ferreira lashing home from 30 yards to open the scoring after 16 minutes.
The home side continued to threaten as we found our feet but after a couple of fine saves from Robert Burch, we hit them on the break with Andy Barcham racing onto Jamie O'Hara's pass and finishing his one-on-one chance in style.
O'Hara and Barcham combined again to set-up Simon Dawkins for 2-1 just before the break and it was 3-1 within a minute of the restart as Barcham squared for Tomas Pekhart to tap home.
Tommy Forecast saved a penalty with 18 minutes left and although an own goal made it 3-2, it was too little too late for Lens.
"We had to solve a number of problems against a very experienced Lens side and we did fantastically well to get back into the game and win it comfortably in the end," beamed development coach Clive.
"They looked threatening and were technically very gifted but after about 30 minutes we got organised, got a good shape, made it difficult for them and looked dangerous on the counter-attack.
"We deserved our goals and went in at half-time leading but with a couple of things to sort out.
"We immediately went 3-1 in front and then it was a case of how you control the game and go on to win it.
"That second half performance was exactly what you would look for against a very good side like Lens. We were controlled, defended well, maintained good shape and continued to look dangerous on the counter-attack.
"As an exercise, it was a first-class experience for the lads and I have no doubts that it will help them in terms of being able to adapt their game in different situations and playing on foreign soil."
A delighted Clive Allen described Tuesday's reserve team friendly victory over RC Lens as 'an excellent all-round performance and experience'.