The New British Prime Minister -- Really?

It looks certain now that there will be a new British prime minister by Thursday.  One of the two remaining candidates dropped out of the race and the current prime minister says he will resign on Wednesday so his successor can be appointed.

It's all nice that there's a new prime minister, but it seems to me that the Tories have made a big, big mistake.  They selected a new leader who supported staying in the European Union in the recent Brexit referendum.  Moving forward, the Tories are going to have to arrange a new relationship with Europe and the world as a whole, and their leader was against the entire endeavor.  There's going to be a lot of distrust in the UK as a result.

Then there's UKIP.  That's the party that argued for independence from the EU for years.  Brexit has been the party's main reason for being.  Had the Tories selected a prime minister closely identified with departing the EU, that person could likely have drawn a big percentage of the UKIP voters into the Conservative party.  Now, with a prime minister who opposed Brexit, the Tories are unlikely to draw many UKIP supporters into their ranks.

It's an inexplicable move as far as I can tell.