In Luxembourg where I live, tax evasion is a civil matter. If you get caught the civil penalties are quite severe and the taxman can take out a remortgage on any property you own and oblige you to pay it but they cannot send you to jail unless they can pin a fraud charge on you.
HRMC are according to friends of mine in the accountancy business, absolutely irrational and utterly stupid. The often opt to bankrupt or prosecute people who 'owe' tax when they would be far better off waiting to let a business get back on its feet.
I fell foul of them when I left the UK to move to Belgium. They came after me for £50,000 in unpaid tax but my accountant said he reckoned I owed them about £5000 but that it could cost as much as £10,000 to prove that to them. He said "do you have £15,000 kicking about in your bank account, looking for a home?" to which I replied "no" and he said "then bankrupt yourself then you won't owe them a penny!". The bankruptcy authorities have no jurisdiction outside the UK unless they engage in lengthy and horrendously expensive action through foreign courts which they won't attempt for a debt as relatively small as yours so...
After a day at the high courts of justice in London I was declared bankrupt. We saw the official receiver the same day and that was pretty much the end of the matter except that HMRC decided they weren't going to accept my bankruptcy - until I had a word with the official receiver who read the Riot Act to the jumped up civil servant from the collections office who was chasing me, then they shut the fuck up!
Chasing a bankrupt for a debt that precedes the bankruptcy is a very serious matter and certainly not something that a civil servant should be doing!