M25 - anti clockwise from junction 4

[Humpy D]

Anybody got any idea why the traffic has been so f***ing awful for the last 2 evenings and is looking like it'll be the same tonight (queue already back to junction 3)?

I know it's half term so this area tends to be a bit busier with families going to Bluewater but it seems especially bad.

I'm hoping it's not to do with the closure of the Falconwood exit slip on the A2 as that is closed until the end of June.