It’s almost five hundred years since Henry VIII fundamentally changed English and Welsh relations with Europe’s supranational political institution, the Papacy. Some things haven’t changed much.

1. They didn’t have a plan in 1527 either. For the first two years of negotiating with the Pope to end Henry’s marriage to Catherine of Aragon everyone just hoped that with enough pressure they’d get a better deal. It didn’t work then and there’s no obvious reason it should work now.
2. Henry’s fundamental problem was that the largest power in Europe – the Holy Roman Empire, incorporating Spain, the Netherlands, the German States and Austria – wasn’t on his side. (Now known as Angela Merkel not being keen on the whole thing.)
3. You don’t want to be the Cardinal Wolsey of this situation (as many politicians appear to be realising).
4. You might think you want to be the Thomas Cromwell of this situation. But a few years later you really really won’t want to be Thomas Cromwell, so enjoy it while it lasts.*
5. The European lawyers are going to make an absolute fortune. Italian legal advisers in Henry VIII’s divorce case boasted of the ‘lucre’ to be made from it and hoped it could be strung out.
6. There will be a lot of shouting in the negotiations. Pope Clement VII, according to a diplomatic report, turned the air blue with his blaspheming over Henry’s ‘obstinate desire’, denounced the king’s ‘devilish inspiration’ and declared that the divorce would cause chaos. That was when he was in a good mood.
7. At the end of the day, the rest of Europe have bigger fish to fry.  As one Spanish cardinal said of Henry’s antics: ‘If for some short while, the Holy See should lose the obedience of one unfruitful isle, it will win it from many other realms of far greater importance.’
8. Henry’s divorce negotiations lasted six years. And that was just for one divorce. Think #Brexit can be done in two? You’re having a laugh.

* Part III of Wolf Hall just got a whole new metaphorical weight. My commiserations to Hilary Mantel. That must be tough.

Read the tortuous tale of Henry’s exit negotiations in my book The Divorce of Henry VIII: The Untold Story (aka Our Man in Rome): vintage | amazon.co.uk | amazon.com | kobo | waterstones