Cheap Fuel

In order to balance things out I've decided that it time to use some 'cheap' fuel, namely some stuff from Morrisons for these reasons:
1. Because it on my route home.
2. I don't have to take a long detour/delay to get there.
3. I have a 'fuel saving' card from Morrisons.
4. Its cheap, cheap, cheap...

So is the cheap store fuel better price per litre then the 'premium' Branded fuel???

(Mpg 50.55) KM per Litre:17.89 Pence per mile:8.00 150 miles for £12

(Mpg 51.71) KM per Litre:18.3 Pence per mile:7.81 138.9 miles for £10.86

So at the moment it looks like I get less mpg but this is balanced out by the lower pence per mile. Though the weather is not as cold, it has been rather wet and windy.