Catrin, it strikes me as a recent construction, based on Fairport's version. Several reasons, including the following- I have read that Lord Darnell appeared first in that version, 'Lord Arnold' having been misheard, and phrases such as 'I've been getting it up all night' sound contemporary, and added for a laugh.

You could e-mail the person responsible for the site, and ask for more details?

I meant to ask you, do you know about 'Little Musgrave'? See this thread for more info.

Noreen