Why? Even if it does come to pass (which I doubt), each country will still feel free to use its own soldiers as it sees fit -- and Anglo-French agreement will come about as often as it ever has.

The proposed forces look likely, under present proposals, to be only 'earmarking' one (RMC or Para, most likely) battalion.

The sticking point would come if France tried to use this as a wedge to get a permanent assigned force (including RAF/RN/Armoured assets) and command structure, and/or access to the full UK intelligence/comms assets, which are presently closely linked to the US.
At that point, I hope and expect, the UK would tell France to stop being silly.

If Blair is being clever about this (though I doubt it), he'll get MoD to make sure this outfit never does anything, and just ensure that it puts a spanner in the works of Franco-German joint ops.
It would be interesting to see what officers think of a post on this unit's staff, if/when it's set up. That'll tell if it's militarily serious or a joke post.

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