Thanks for the comments folks, the Summit's a nice grill for sure & now I have a pair...lol the WSCG & E-670. I'd only cooked Mince Pies (at Christmas) on the Charcoal & have pretty much zero experience with Charcoal.
I didn't have that long to cook Kristof as we had the son & his family round screaming for food...so went for a quicker cook.
I found it perfect, may try a longer cook at some point but don't see the need as this tasted great! The thing I may not do next time is the crutch as whilst I had bark the crutch softened it some.
Personally, I've not looked at the Harry Soo method, but will do, thanks for the heads up Dale!