Lots of pontification, but little substance.
Who said put half of the artillery in front? 10% at most in camouflaged positions with orders to engage when close enough, having switch positions to move to after the battle to avoid getting plastered next go around. IOTL we have examples of the British using rather inflexible attacks on fixed positions and getting slaughtered at Halfaya Pass, which, given its compressed battlefield and the relative strength of each combatant in Operation Compass, its not hard to see that forcing it in 1941 is going to be hard; the British were able to exploit the gapping gaps in the Italian lines around Sidi Barani IOTL to wipe out their forces, but won't be able to ITTL, so will have to push right through and into much greater firepower than they themselves could muster.
http://en.wikipedia.org/wiki/Operation_Compass
1,600 artillery pieces concentrated at Halfaya against 120 British guns is going to give them a lot of flexibility to use guns forward, while having 1,249 aircraft for use against the British; even if the artillery is totally ineffective bomb dropping aircraft, including dive capable biplanes, are going to be able to stop the British tanks if need be. The British did not yet have the logistics to move around the southern flank of the Pass, which was pretty far south considering the necessary detour:
http://upload.wikimedia.org/wikipedia/commons/6/63/WesternDesertBattle_Area1941_en.svg
You assume that the British have been putting lead in their tea - why would they attack while so weak. The victories over the Italians was a battle of manoeuvre not a battle of attrition.
So in practice they could move as many guns as they liked....the British would not have attacked....enjoy the flies lads