[scott_w]

True unlimited PTO can exist in the UK, though the "unlimited" PTO can't, as employees can't agree to less than the statutory minimum.

That said, unscrupulous employers try to get around this by putting stupid requirements on taking PTO that practically mean taking your legal allocation aren't possible. Things like "we need minimum staff levels to cover" and, shockingly enough, you don't have enough staff to actually give out everyone's PTO. Combine this with requiring long timeframes to book it and your manager "forgetting" you had PTO booked and insecure job contracts and you have a recipe for grinding your staff to dust.