Blue bird with light chest Sheffield

Hi all new on here. But need some expert opinions on a bird I saw today at dungworth in Sheffield. 

I'm not a bird expert but know all the common garden and countryside birds. I also know what a kingfisher looks and fly's like because I'm an angler, so it's not one of those.

It was slightly larger than a king fisher, morlike a small starling, It had a blue back and a very light almost white breast. It was quite a quick flyer not like any of the tit family.  I watched it flying for a minute or so from about 50m away then it disappeared behind some trees.

I've never seen one before and wondered if any one can shed some light on my spot? I've googled it and it looks like a mountain blue bird or very similar. I'm going to try and find a video of one in flight on YouTube.