Sorry, I should have made it clear that I didn't know how the blue texel colour transmits onto other coloured sheep.
Onto white sheep of similar breeds, so onto a white texel, then as the blue is recessive, you'd expect very few blue or black sheep in the next generation. But where there are coloured genes in the gene pool, then you will get coloured offspring - 50% in a second generation. ((Blue x White) x Blue)
What I don't know is whether the gene for colour is the same in the Blue Texel as in the Black Wensleydale, where the coloured gene is also recessive, but may or may not be the same gene. (I have two Black Wensleydale ewe lambs, so would be interested in getting coloured Wensey x Texel lambs from them in due course.)
And similarly, whether the colour in a blue texel tup would give coloured lambs from a Manx, a Castlemilk, a coloured Shetland, and so on. Or only as many coloured lambs as a white Texel would.