The race was started last Saturday in the city, with the birds heading to the North East of England, but some pigeons were still returning home yesterday (Thursday) - when they were scheduled to finish a few hours after the race has started.
Investigations are on going as to what caused more than 10,000 pigeons to disappear - with experts looking as to whether a possible change in the Earth’s magnetic field caused the flock to vanish.
Ian Evans, chief executive of the Royal Pigeon Racing Association (RPRA) said the event had been unprecedented.
He said: “There were races across all parts of the country, including one that started in Peterborough that were affected.
“We always take care to liberate the birds in good weather conditions, and while Saturday was cloudy, it was nothing out of the ordinary.
“The pigeons were taking part in short races, and most should have been home in a couple of hours.
“But at a time when we would expect more than 90 per cent home, we only had 10 per cent home.
“We are looking at magnetic field activity, but at the moment there has been no credible explanation as to what happened.
“We are still scratching our heads.”
Mr Evans said that since the race had taken place, birds had been arriving home throughout the week.
He said; “We were still getting reports that some were returning home yesterday.
“It can be that some find their way to someone else’s loft, and they are cared for until they are fit to be released, then they are liberated and find their way home.
“We think most are home now though - but it has taken a long time.”
Mr Evans said he had never experienced anything like what happened before.
He said: “I’ve had pigeons for 36 years, and I have never known anything like it.
“Something might have happened 50 or 60 years ago, when weather forecasting was not as good, but with the weather forecasting available now, it is unprecedented in modern pigeon racing.”
Mr Evans said perfect weather for pigeon racing was clear blue skies, although some cloud was OK, as long as there was good visibility..
Pigeon racing sees pigeon owners travelling to a spot, with pigeons using their homing instincts to travel back to the loft.
Rather than the first bird home, the winner is the one with the fastest average velocity. Mr Evans said it was a sport with ‘one start line but thousands of finish lines.’
There are currently around 19,000 members of the RPRA, and around 30,000 people who take part in the sport in the country.