Assuming you're referring to the version on "Awkward Annie," then the shared vocal is by John Hudson, a well-known English opera tenor, also a Barnsley boy.

https://www.theguardian.com/music/2007/sep/14/folk.shopping

https://19silverlinings.wordpress.com/2020/08/27/im-probably-the-best-known-opera-singer-ever-to-come-out-of-barnsley/