This whole fish & chip thing is funny. I had a great chippy near where I lived before I moved to the sticks. You had a choice of Cod, Haddock, Plaice, Skate and the unbeatable 'Rock'.
Yonks ago, I travelled with my 'Cov' girlfriend to her brothers wedding in Leyland and the night before, the food of choice for us guests was fish and chips, so off I went with the orders, which for everyone other than me was Cod or Haddock and when I got to the chippy, it had one price for fish and chips, which I thought was great, until I realised it meant all they sold was Cod.
So with that mind numbing lack of choice, its no surprise to learn our northern breathren have had to find imaginative way's to make the dish interesting!
On saying that, the best fish and chips I have ever eaten was from a place in Sheffield and yes, it included mushy peas. The worst is usually accompanied by the words, 'Harry Ramsden'.
BaaBaa, did I mention the slice of lemon provided to accompany the vinegar?