The thing is, Raspberry PI is not even out yet and it already has a direct competition(Rhombus-Tech), that it does intent to use the A10 for its board and price may end up cheaper than Raspberry...
I'm not sure that Rhombus-Tech is a direct competitor. Their primary goal is to get devices (tablets, netbooks, desktops, settop boxes) that can be programmed with entirely free software. As part of that they're designing a modular board that can be plugged into any of those things built with a standard connector, and then the guts of devices can be replaced/upgraded as chip technology and/or GPL compliance advances.
It's mostly coincidence that one of their modular boards could be used in the same way as a Raspberry Pi for teaching and hobbyist use (though some might say that a programmable tablet would be a pretty good incentive for kids to learn programming.)
While UK production of the chip isn't something they could deliver (currently) while meeting their other goals, it is fair to say that stimulating British business is part of their plan. It's just that it's Free Software developers and the businesses that buy their services and hardware to run their software that will benefit, rather than chip manufacturing plants.