BA sent this early this afternoon about my mid afternoon flight :

‘Thank you for choosing to fly with British Airways.

Please be advised that your flight may be delayed today because of Air Traffic Control restrictions in the London area.

If you have a connecting flight as part of the same ticket and there’s a chance you may miss your connection, we'll automatically rebook your onward journey. Please check ba.com/managemybooking.

We look forward to welcoming you onboard soon’

All looks on time apart from a 20 minute delay