Swallows and Harriers do fit over 266s. 
They're tight though...as in so tight if one of the little 'butterfly' springs pops out of a Lucas caliper it scores the rim and makes a hell of a noise. 
I'd personally go for Lucas 266s if you can, easier to chose pads for and look better imo. Those Bosch 266s only seem to come on ph3 1.8s, all my other ph3s have been Lucas!
They're tight though...as in so tight if one of the little 'butterfly' springs pops out of a Lucas caliper it scores the rim and makes a hell of a noise. I'd personally go for Lucas 266s if you can, easier to chose pads for and look better imo.
Those Bosch 266s only seem to come on ph3 1.8s, all my other ph3s have been Lucas!