Hi

An Allied GC is something I've been looking forward to, so it's nice to see it's being talked about. Just some random thoughts:
I'd agree that 'Free' contingents need to be in there somewhere. One of the great things about AC was that some SE units were unique nopurchase units, rather than being normal units with a fancy paintjob and some bonuses. This could be a way, not only to to get some historical allied contingents in, but make sure they're used. So, for example, the player could get a SE Polish mountain unit ( The Carpathia Brigade), Free French Sahara troops/ Foreign Legion ( switchable troops like LRDG, but please with at least a spotting bonus over normal infantry this time), together with more standard units like a Czech SE Spitfire squadron etc. For that matter, some SE Ghurkhas would be nice...
On capturable equipment, there's no doubt the British did use foreign equipment, but it needs to be kept real - the Western allies were thin on German tanks, with just the odd trophy here and there (except for the Poles in Eqypt with their MkIII's...but they never went into action with them, historically). Perhaps each Campaign could have one bonus scenario, accessible only by a DV in the proceeding scenario, with one capturable item. In France, some BEF units were given a bunch of French 25mm AT guns to make some use of (somehow...), captured Italian tanks were used in early 1941 both by British armoured units and Australian divisional recce units, the Tobruk garrison used captured Italian AT, AA and artillery, after Alamein 8th Army had a unit of captured 88mm guns as part of its 'siege train' ( they being mightily impressed by the effect its airbursts had on dug-in infantry rather than using them for AA or AT). In particular, any Recce vehicles or halftracks were swooped on by those units not gifted with them by their TOE.
I'd agree with the posts above that a joint British-US Grand campaign would be a bit disappointing and lead to the 'cherry-picked' cores seen in AC, with Churchill's backed up by US motorised 155's etc. Best keep them separate in my honest opinion. The campaigns could go something as follows (with suitable pruning), assuming one at least one fictional and/or bonus scenario per campaign.
UK & Commonwealth:
1940 - Norway, Belgium, France to Arras. Bonus scenario following DV at Arras? Campaign branch - Operation Dynamo (battles around Dunkirk) or Operation Ariel (battles in south of France. Fictional scenario - Sealion (what else?) - To desert for Operation Compass/ Bardia.
1941 - Tobruk/Beda Fomm. East Africa/Keren. Campaign branch - Not-so-soft Underbelly (Greece and Crete) or Enter Rommel (Border battles/Tobruk/ Brevity). Battleaxe. Bonus scenario - Syria? Fictional scenario - defence of Gibraltar against Spanish? Crusader - Bir el Gubi, Sidi Rezegh, Totensonntag, Breakout from Tobruk.
1942 - Rommels counterattack. Bonus scenario - Madagascar? Gazala - Bir Hacheim, 150 Box, the cauldron, Knightsbridge, 50 Division breakout. Fictional Scenario - Malta? Possible campaign branch: 'Everywhere Dispersion' - Mersa Matruh, defence and breakout, or July Nonsenses' - First Alamein - 'The Hotbox', 'Ruin Ridge', Op Bacon. Alem-el-Halfa Ridge. Second Alamein - Lightfoot, Thompsons Post, Supercharge, Snipe, Ariete's last stand. Fictional scenario - Fuka?
1943 - Agedabia, Tripoli. Campaign Branch - 'First Army' - Medjez-el-Bab, Steamroller Farm, Fondouk Pass, Longstop Hill, Operation Vulcan. 'Eighth Army' - Medenine, Mareth Line, Supercharge II, Gabes Gap, Enfidaville. Sicily - Primosole Bridge, Catania Plain, Race for Messina. Italy - Campaign Branch 2 - Historical (Drive for Salerno or Monty's Plan (8th Army lands at Salerno alongside 5th Army). Bonus scenario - Operation Slapstick? Taranto/Foggia - Sangria River.
1944 - Monte Cassino. Bonus scenario - 10th Army 'kessel'? Normandy - D-Day, Villers Bocage, Hill 112, Caen, Goodwood, Totalise. Bonus scenario: Falaise Pocket? Campaign Branch - 'Second Army' - Seine crossing, Antwerp Port/Brussels, Arnhem or 'Maple Leaf' - Le Havre, Albert Canal, Scheldt estuary. Fictional scenario - 'On to Rotterdam!' Walcheren.
1945 - Veritable - Reichswald, 'Blockbuster', Hochwald. Rhine Crossing, Advance into Holland and Germany ( Campaign Branch). Bonus / Fictional Scenario's - 'On to Berlin? 'No Entry' (against Russians trying to enter Denmark).
US - I won't presume to suggest to Americans which of their battles should be represented, but a broad outline:
1942/1943 - Tunisia/Sicily/Italy
1944 Overlord: Normandy, France (Possible campaign branch between Huertgenwald and Metz?)
1944 Wacht am Rhein: Just the Ardennes...there's enough fascinating actions to justify a campaign of its own.
1945 Rhineland, Remagen, Ruhr Pocket, Drive to the Elbe (and other places).
One further point - to avoid the Allied campaigns being too easy (as can happen in AC) , the availability of allied equipment really needs to be modified to ensure they are only available when they were in widespread use, rather than just sitting somewhere. Churchill's were not deployed in significant numbers until March 1943 in Tunisia. They certainly weren't swanning round the desert in Op Crusader, watching the Typhoons fly over. Nor was Monte Cassino over-run by masses of Sherman Fireflies and Crocodiles.
Oh...and a fair number of the maps need to be large enough so that anyone who relies on Mv-3 Matilda II's and nothing else for their armour is in for an unpleasant shock :p
Just some thoughts as I said. Thank you to anyone who takes the trouble to unscramble them.