@gettingonabit
You are correct that the economy wasn't in great shape before BREXIT, despite what Osborne claimed.
Tax receipts have not risen as much as was expected, because (as you say) wages have remained low. Additionally, some of the wealthiest aren't paying their fair share.
However, the biggest problem is lack of demand in certain areas. People paying high rents in insecure jobs will put off buying a new car, getting their bathroom refurbished or whatever. They might even put off having their hair done quite so regularly or employing a cleaner/gardener.
Meanwhile, people with shares or buy-to-let properties are making even more money. Asset strippers can buy up struggling companies and increase their own empires, often losing jobs on the way. These people have too much money to spend on the high street, so they buy foreign shares or more property, etc. Their money isn't finding its way into the economy to pay for real jobs. The BoE aims for an inflation rate of 2%.
Past forms of quantitative easing and low interest rates didn't get much further than the banks, so what the Bank of England is trying to do with negative interest rates is to stop people hoarding their money and get it into circulation. It's a risky strategy, because interest rates are already so low.