Well if they hear about the 20 tanks in Karbala, I am sure that more will show up!
LOL!
I'm not gonna get all bent out of shape about this one. This same kind of thing happened in WWII when the British General Staff thought that American troops were sub-par.
Anyhow, the simple response is this:
British troops are magnificent. Why don't we swap places. US troops will take charge of the Basra region and British troops will take charge of the Sunni Triangle and Baghdad.