Hi Squiggle welcome to the community from Sheffield.
I don't see why another species of bird wouldn't nest in the same bush if it's big enough that they both have their own space.
Keep us updated if you see anything but don't go poking about in the bush to see or you may spook the Blackbird into leaving the nest
Many thanks. I wish I had a camera in that bush. But I won’t go poking around in there. I will be intrigued to know if she used one of the Simon King nesting/roosting pockets I hung in there and around the garden. Will she be pregnant now or do they build then get down to ‘business’? A male arrived yesterday.....tried to pluck some dead leaves from a vine..... didn’t succeed....... then flew off! Is she really going to do all the work! A male also arrived [same male?] with ‘another woman’! Ddin’t Go down well.