Stoat or weasel?

This cheeky chappy…

was photographed on one of our bird boxes this week. Is it a stoat or a weasel?
Well we know that weasels are “weaselly” recognisable -while stoats are stoatally different. So this is obviously a weasel. Smaller than a stoat and no black tip to its tail. Did he find any eggs in the box?