Royal Mail have advised that not all mail was processed to schedule yesterday at its Gatwick and London Central Mail Processing Centres. Customers should expect delays in the following areas:

Gatwick Mail Centre: Some mail posted in the BN and RH postcode areas yesterday for delivery today in other parts of the UK.
London Central Mail Centre: Some mail posted yesterday in other parts of the UK for delivery today in the EC, N, W1 and WC postcode areas.