I had a response to your mudcat query. Can you please pass it on ?
"They (singing nights) happen in Penzance every Wednesday - either at the Bath Inn, or at the Admiral Benbow - they alternate. Here's a link to the Bath one http://www.bathinnfolk.co.uk/
Bath Inn Folk Penzanace
www.bathinnfolk.co.uk
Bath Inn Folk Penzanace"
Bath Inn Folk Penzanace
www.bathinnfolk.co.uk
Bath Inn Folk Penzanace

11:48
Anne K Kennedy Truscott
I've had another response : Singers' Night every Wednesday in the Wellington Pub in Boscastle, which is at the opposite end of Cornwall from Penzance !
It is not far from Tintagel.

Hope the above is some help.