In Hertfordshire there are a few places, prices listed are for reguler Gas, first is shell in hunton bridge thats 135.9 PL. Next is shell in Gaston dome round about and thats 133.9 PL. There both not far from each other and the cheapest I see for shell fuels.
thought id get this a bit more up to date... as of the 25-12-2014 shell v power only in my car and its down to 1.19!! its f#*king brilliant! i nearly get 17 litres for 20 quid!! KEEP COMING DOWN PLEASEEEEE