Flash sale on Eurostar with tickets for £35 each way

Eurostar has a flash sale for the next few days, offering tickets from just £35 each way for travel between London and Lille, Paris, and Brussels.
The offer is valid for trains between Wednesday 13th March and Thursday 23rd May, with a few blackout dates, and the flash sale runs from today until Thursday (7th March).
Although they are on sale, the discounted tickets still qualify for Eurostar’s policy on changed travel plans and can be moved to a different date with no exchange fee up to seven days before travel. You will need to pay the difference in ticket prices if there is one.
The flash sale is here.
A tip, if you fancy a day-trip to Paris, then mid-week seems to be the best to get £35 fares in the morning and evening. If you select a weekend, then the outbound trips tend to be later in the day, so you’ll need to add a hotel and return the following evening.
Black-out dates apply:
London to Paris: 28/03/2024, 29/03/2024, 01/04/2023, 05/04/2023, 03/05/2024. 11/05/2024, 12/05/2024, 20/05/2024.
Paris to London: 01/04/2024, 06/04/2024, 07/04/2024, 08/04/2024, 13/04/2024,14/04/2024, 06/05/2024, 08/05/2024.
London to Lille/Brussels: 28/03/2024, 29/03/2024, 01/04/2024, 05/04/2024, 03/05/2024, 11/05/2024, 12/05/2024, 20/05/2024.
Lille/Brussels to London: 01/04/2024, 06/04/2024, 07/04/2024, 13/04/2024, 14/04/2024, 28/04/2024, 06/05/2024, 08/05/2024.