POST boxes were filled to overflowing as Worthing residents rushed to send off their census forms and avoid a possible £1,000 fine.
Despite people being able to fill in the paperwork online for the first time, thousands chose the traditional method.
But post boxes all over town could not cope with the deluge, prompting fears that thieves could reach in and steal envelopes spilling out of the apertures.
Even the post boxes at the main post office in Chapel Road were reported to be packed.
James Feest, of Goring Street, Worthing, said: “Having dutifully completed our census return on Sunday, we went to post it at around 10.30am on Monday, only to find all the boxes near to us filled to overflowing, so much so we could not post the return and six other envelopes.
“The situation at Tesco’s main store at West Durrington was worse. They had to temporarily seal the box as it was so full.
“I tried again at 3pm, only to find the boxes in this area still full to the brim and uncleared. However, I did find one a little further afield that had just enough room.”
The last census for England and Wales, conducted by the Office for National Statistics, was in 2001. The latest count involved around 26 million households which had until Sunday to fill out the forms.
However, a census spokesman said: “Although the day to fill out the forms was Sunday, the deadline is a little way off yet.
“Census collectors will start on April 6, visiting the houses of anybody who hasn’t returned the forms to give any help.”
The census website warned it was a legal requirement to complete the forms and non-compliance could result in a criminal prosecution and a £1,000 fine.
A Royal Mail spokesman denied the postal service had been caught out and said collections had been stepped up to cope with demand.
He said: “I spoke to the delivery office manager at Worthing and she tells me there were major postings overnight on Sunday and Monday.
“It wasn’t a matter of boxes being full. Some of the boxes, when you post large items, they catch in the middle of the boxes and actually start building up.
“There was a collection every hour-and-a-half on Monday and that’s going on today (Tuesday). They should be able to deal with the very large amounts of items that have been posted all at once.
“The manager is only aware of four instances of where it got reported to her that boxes that were overflowing or full. Those boxes were tended to immediately. We are organising significant extra relief collections to deal with these items.
“I understand that Worthing has a lot of very small (wall) boxes. At the main post office they have larger boxes which should cope.
“Tesco’s box always fills up very quickly, even under normal circumstances.”
The census spokesman said: “Customers who notice post boxes are full can report them to Royal Mail on 08457 740 740 and they will arrange for the box to be cleared as soon as possible.”