Black Redstart?

Hi, today about 1500hrs I saw a new bird to me in the garden (South Cambridgeshire). It was perched on a low garden light on the edge of the lawn, with charcoal/ash grey plumage, a black beak and I think black legs. What struck me was that the "outer" tail feathers were a reddish-orange under black/grey "inner" tail feathers. A Black Bird appeared and so it was clear the other was much smaller, perhaps Robin size but much more elongated. It also seemed smaller than a young Starling (we have these nesting each year in our garage so am used to them appearing brown-black, but this new bird was a similar size to a juvenile Starling, with similar beak shape but perhaps narrower).

When it flew off it kept low to the ground, with the tail feathers very visible in the flash of flight before it was gone. Was this a Black Redstart?