Cheers Chris, really happy with how it's looking now, and even my fears of the tyres being a bit skinny, have now gone, they look fine...
I did some frame measurements for Nick, before I bought his Magura's,
Top tube is 23.5"
Down tube is 27"
Seat stay is 20"
Chain stay is 17"
And it would appear there's only about half an inch in it, whether you run seatstay or chainstay routing for the rear brake.