I haven't been following the things happening in Britain as closely as other people. I don't really have an opinion one way or another. If the country feels they need to raise taxes, I don't see any reason why they shouldn't raise taxes. I assume that they are a sovereign nation and can make their own decisions without people from the US breathing own their back. They should be allowed to make their own decisions and their own mistakes.
The economy of the United Kingdom is going to take a hit following the country's vote to leave the European Union. A declining economy means that government revenue will fall as well. Substantial government deficits will further weaken the nation's already fragile economy. Therefore, in order to protect the financial stability of the British government, the country will need to raise taxes.
No raising taxes right away may anger citizens who opposed leaving the EU. Plus raising taxes is usually bad for a country's economy, because it puts less money in people's pockets. Raising taxes can also cause inflation because if businesses have to pay more taxes they are likely pass the cost on to consumers.
Britain should not raise taxes following the "Brexit" vote unless it is truly a necessity. Things change all of the time and taxes are one of those things. It is highly likely that taxes and their distribution and use needs to be addressed but they do not necessarily need to be raised in order to get the money where it needs to go.