IHG just announced a flash sale with at least 30% off on Best Flexible Rate in the UK and Europe. You need to book between September 22nd 2020 and October 14th 2020. This booking window is much longer than what you expect from a flash sale. But then nothing is normal in these times.
You need to book at least 3 days in advance for stays up to April 20th 2021.
This is a fully prepaid rate. However, the booking can be amended or cancelled 14 or more days before the arrival date at the hotel.
IHG has been running such advance booking flash sales for some time now. And they have been little relaxed with cancellation policies this time due to Covid.