Much depends here on which GDP series you look at; if you use the World Bank figures with 2000 prices, the UK is ahead of Germany. If you use current-year prices, Germany is ahead, but only since 2008. Looking at that data, getting the UK into the lead is easy; all you have to do is match French and German productivity growth, which basically requires fixing British industry. Okay, maybe 'easy' was the wrong word. But the problems are well understood.
France is more interesting - it doesn't seem to be so much France underperforming as Germany overperforming. By and large, France and Germany keep pace quite closely, apart from the period 1990-2004 and post-2008. The 1990-2004 one is odd - given that it's the 15 years or so that Germany was reunifying, I'd expect the GDP per capita to drop off (or at least stagnate) then rebuild. Instead, France stagnates, whilst Germany goes through a boom and mini-recession. The crucial years seem to have been 1990 and 1991; if German productivity growth in those years is closer to the European mean, that knocks up to 6% off their per capita GDP.
Post-2008 is similar; Germany, for whatever reason, bounced back from the financial crash much better than Britain or France. Regress them towards the mean, perhaps with less-effective leadership, and that's a fair bit off the German GDP. Taken together, those should give Germany a GDP slightly lower than France, with a PoD around 1990.