We\’ll let one of Ritchie\’s commenters do the heavy lifting here:
Gauke isn’t in conflict with his boss, you’re confusing some of the figures:
Assume the tax gap is £42bn, as stated. That’s close enough to Gauke’s £40bn if £84bn is “close enough” to your estimate of £95bn.
George Osborne referred to £14bn being the figure for tax avoidance AND evasion together. As you say, that’s about 33% of the tax gap, or one third.
The document on tax avoidance talks about avoidance only, not evasion, and estimates it at 17.5% of the tax gap. Which is about one sixth of the tax gap, and is about £7bn. That’s consistent with Gauke’s figures, so Gauke is agreeing with Osborne’s figures, as he’s talking about £7bn of avoidance (not avoidance and evasion).
If avoidance is around £7bn then evasion must also be about £7bn, being the other half of the £14bn and is therefore consistent with the other one-sixth that Gauke refers to. The two one-sixths make up one-third, and so you get your £14bn out of £42bn.
So there’s no real inconsistency. Certainly not if you think £84bn is close enough to £95bn.