Yes thanks, a very useful source although it does exclude the cigar-shaped tank often carried on the Continent – unless that more tapered shape in the diagram is meant to include the stubbier one. As I understand it the aft tanks were only introduced near the end of 1944, and were rejected by Fighter Command (ADGB?) because of the stability problems, and their understandable judgement that there was no purpose in flying out further than they could fly back on internal fuel after combat (which is behind my earlier comment that the Mk.VIII would have been better than the Mk.IX – not only more internal fuel but ahead of the aerodynamic centre and thus stabilising). The aft tanks did however prove useful with 2 TAF where the centreline position could be used for a bomb so the aft tanks served the same purpose as a centreline tank – i.e. use first. The real answer was the larger tail and tailplane which was eventually introduced on the Mk.22, by which time any need for long range had disappeared and the use of aft tanks was actually banned on those aircraft fitted with them.