The 2016 referendum WAS and IS binding, David Cameron who was prime minister at the time said it was a one off decision for the British People. when we voted to leave-he wanted to remain- he resigned and Theresa May another remainer was elected by the Conservative Party, I don't think she ever wanted to leave the EU but to not do so would result in rioting in the streets. it seems a deal has now been agreed between the UK and the EU, not exactly the one we wanted but its the one we've got, whether TM can get it through parliament is another matter, the place is full of remoaners. I have never seen so many traitors in one place in the whole of my life.
In the UK, parliament has sovereignty hence referendums are advisory rather than legally/constitutionally binding.