Is this a swallow?

Saw a bird today that I think might have been a swallow. I’ve never seen one before so I just wanted to check beforehand, it seemed a little small (bird was finch sized). Might be pretty obvious. Didn’t see too much but I will keep it short so here’s a list: 

Where: Rural village flying around about lamppost height 

Size/Shape: Finch size with long curved wings and long tail bits

Colour: Mostly black with lighter grey 

Are they normally that small? Thanks, Ellis