What is this please?

I have no memory of planting it. Only one has appeared. It's about 1 foot tall and the same across. It 'crept' up on me and started to flower a couple of weeks ago.

 

?Sedum spectabile? or perhaps one of the Sedum rupestre types which are everywhere at present.

 

Thanks Palustris, guess a bird brought me it. I quite like it so I'll google it and see if I (or Boss lady) want to keep it.