The second class performance of Brighton and Hove's postal system is exposed by The Argus today.
Our investigation reveals while mail sent across the country arrives on time, one in ten first class letters staying within the city limits arrives late.
Businesses believe delays could be costing them thousands of pounds while late letters have also been blamed for inconveniencing people trying to pay bills by post or organise meetings.
Earlier this month, The Argus posted 70 first class letters from 35 different pillar boxes to ten addresses across Brighton and Hove.
Ten letters were also sent to destinations across the country.
Every letter sent outside Brighton and Hove arrived on time.
But one in ten of the letters to addresses within the city arrived at least one day late. The 90 per cent success rate falls slightly short of Royal Mail's target of 92.5 per cent.
Public confidence in the postal system has already been damaged following the Channel 4 Dispatches programme which claimed to uncover fraud and theft in mail centres.
The company also faces a £40 million fine for failing to meet performance targets and has come in for criticism since the abolition of the second post earlier this year.
Keith Bryden, chairman of Hove Business Association, said: "You expect post in the morning and it isn't coming in the morning. It is very serious."
As part of our investigation we posted letters to York, Maidenhead and Plymouth - 278 miles, 79 miles and 224 miles from Brighton and Hove. All arrived the next day.
Yet a letter posted in Churchill Square, Brighton, took three days to arrive in Wish Road, Hove, two-and-a-half miles away.
Letters from Hollingbury and Dyke Road in Brighton destined for Hove were also delayed by up to three days.
Brighton Pavilion MP David Lepper said he received a number of letters at his Preston Road office yesterday which had been addressed to other businesses.
He said: "It looks like it is a bit of a shambles, to be honest."
But Hove MP Ivor Caplin defended the Royal Mail's record and praised postal workers, who he said are conscious of the need to deliver on target.
"What The Argus research shows is that broadly they do, although there is still some work to do."
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