Surnames Quiz

[denquiz]

Just stuck on one last clue - answers are surnames (most appear to be of Scots origin):

4. Black or lock etc

(I'm wondering whether it could be something like Duff/McDuff as that means dark/black but can't find the link to lock...)

Any help/clues etc would be gratefully received! Many thanks!

[grasscarp]

Smith

[denquiz]

thank you muchly, grasscarp! How did I not see that ...!!

[grasscarp]

I tried to think of a clue but failed so gave answer. Happy to help.

[denquiz]

Thanks, DocSausage, I was thinking like you re the Gaelic Dubh anglicised as Duff but I think grasscarp's answer is more likely to be right because you have Black-smith and Lock-smith, etc..