Anyway, I decided to try a Duvel type beer after getting the All Grain bug and the recipe is straight forward enough. Basically I had 84% Pilsener malt, 16% Candi sugar, 90 minute mash at 65C and a 1.2 litre starter of WLP 570. I got 80% efficiency and a wort of 1078 ( aimed for 1070 ! ) so I expected to end up with a beer of maybe 8% abv if the yeast performed well.
I was worried the starter might be a bit small but it was well in date and it took off well and was pitched in to a final target volume of 11 litres. Ramped the temp up from 20C to 24C over a few days and after a week the gravity was at 1012

I racked to secondary after 2 weeks, turned the temp down to lager ferment temp, 10C, and left it in secondary for another 2 weeks. I've just finished bottling about an hour ago and after taking a final hydro reading I've bottled with a final fg of 1008

I know my maths is crap but I reckon thats around 88% attenuation? and a beer of 9.3abv. I've got to try and forget about this bad boy for a couple of months I reckon to give it a chance to condition properly or get another brew on to take my mind off it. Time for another order methinks.