Thousands of homes suffered delays to their postal deliveries after a power cut at the busy Royal Mail sorting office in Gatwick.
Staff at the office worked hard to sort much of the mail by hand to clear the backlog destined for addresses across Sussex.
Many homes experienced delayed post services yesterday because of the problems at the sorting office, which deals with more than two million letters and parcels a day.
However, staff managed to keep the post moving and many homes received their mail on time.
There was no power most of the day at the depot and all the post had to be sorted by hand or redirected to other sorting offices in Tunbridge, Twickenham and Harrow.
A problem with the National Grid, which began at about 8.30am, left the main sorting office for Sussex without power throughout the day until 6.30pm.
Sussex postcodes of RH and BN, which includes Brighton and Hove and much of East and West Sussex, suffered the longest delays, including some villages in West Sussex, like Chelwood and Lowfield Heath.
The 800 staff worked frantically to sort the mail by hand or send it to other centres for processing.
Royal Mail spokesman Patrick Breen said: "We apologise to customers if there has been any delay in the mail but we hope they understand it was due to circumstances beyond our control.
"We finally got power back at 6.30pm. We lost touch with the National grid at 8.30am and, although this came back at 10.30am, our own emergency generators blew a fuse and had to be repaired, which took all day.
"All the mail collected and taken to Gatwick was sorted by hand and would have arrived on time. They worked their socks off at Gatwick to make sure the mail kept moving.
"But, some of the mail from BN and RH went to other sorting offices. There may have been delays with batches sent to other centres.
"It is rare for this sort of thing to happen but we do have contingency plans"
The backlog has been cleared and the sorting office was running as normal today.
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