Do you haggle when buying currency?

How many thousand pounds worth are you buying?

Yes, I always haggle, or at least ask for a better rate. Depending on where I am (not in a bank of course), and if I have a decent amount to exchange.

But I would never buy foreign cash in the UK, when there are cards available that give the prefect rate, such as Revolut, Halifax Clarity etc.

In the UK I have only ever sold foreign cash for pounds, which is what you mean by 'by back'. The rate is higher because they are asking for more of the foreign currency per pound than the mid-market rate, just as they are giving you less of it when you buy it - that's how they make their profit. Even then there's no harm in asking for a better rate, you may succeed if they see that you know what you're talking about. If they appear offended you are in the wrong place.

A local travel agent told me once that whenever I had money to change to shop around and then come to them and they will do their best to beat the best quote.

These were reasonable sums at the time though but they have done similar for smaller sums and have generally succeeded.

As Gloomendoom hinted however, our changing money days are now mainly over as no exchange company can come close to the rates our Clarity card gets with overseas ATM.

We now keep an envelope full of the leftover currency from our previous holidays which is usually enough to last us through to the airport and to the first overseas ATM.