Vince Cable skewered as ex-Revenue chief ridicules Clegg's claim he can fund £17bn tax cut | Mail Online.

The Mail is having a lovely time (in their opinion) attacking the Lib Dems.

Yesterday George Osborne produced a letter from Chris Tailby - former head of avoidance at HMRC and before that a partner at PWC - saying HMRC could not raise £4.7bn from an anti-avoidance campaign, as claimed by the Lib Dems.

I stress: £4.7bn - not £17bn. The rest of the Lib Dem changes are tax increases and unless we're saying those are now outlawed I don't think any one is disputing they raise money.

I know Chris Tailby. We've worked together. I respect him. But on this occasion I have to say he is simply wrong.

I am well aware that there are those who would like to say my estimates of £25bn of tax avoidance, £70 billion of tax evasion and £28 billion of unpaid tax to HMRC in the UK - totalling £123 bn in all - are wrong. The trouble for them is they can say it - but even HMRC admit the unpaid tax figure and £40 bn of the avoidance and evasion.

HMRC also admit their basis for estimating tax evasion and avoidance on income tax and corporation tax is wholly inadequate. That's partly, I'm afraid to say Chris Tailby's fault. He never adequately defined the problem he was tackling when in the job.

This gives us a range for tax recovery of between £68 bn and £123 bn then, with some saying I'm at the high end and HMRC effectively admitting they understate the case.

So let's compromise for a moment on uncollected tax of £100 bn.

Is anyone really saying it's beyond the wit of HMRC to recover just 5% of this sum.

If they are then I have just one thing to say - they're wrong. I set out how to do it here.