i always associate parsley sauce with fish that's not been battered and fried so I'm struggling with the idea of it in a fish and chip shop. Having said that I'd probably give it a go if it was on offer (and I'd made the 5500 mile trip back to England. If you get it going Riley, let me know where and I'll drop in when I come over in November!)
I remember when the fish and chip shop first opened at The Brecks in about 1960 and it was very good. Tried it a few years back and it was barely average. The XL in Wickersley as already mentioned was the traditional top spot on the east side of town for many years. No longer apparently.