It took less than 10 minutes for water levels to rise to waist height in the basement of the Charles Bradlaugh, in Upper Mounts, during the downpour.

Bar manager Gavin Wise said: "We checked the cellar when the heavy rain started and could see drips coming down so we thought we'd better keep an eye on it.

"Five or 10 minutes later, it was four feet deep.

It was absolutely incredible. We tried to bail it out but it just didn't seem to be having any effect."

The force of the water had been so powerful it had burst a hole in the floor of the basement.

"We've got about 130 barrels down here and a lot will definitely have to go because they were completely submerged," Mr Wise added.

The downpour also sparked a scare at one of Northampton's most prized historic houses when a neighbouring building was flooded.

Volunteers involved with the Charles Rennie Mackintosh house at 78 Derngate were relieved at the escape, despite floodwater getting into the basement of 82 Derngate next door.

Simon Mitchell, a volunteer assistant at 82 Derngate gallery and visitor centre, which was officially re-opened this week following an extensive refit, said the damage had been restricted to the basement.

He said: "The fire brigade came out to empty it and we have had to call in specialists with dehumidifiers, but thankfully there is no significant damage.

"All that was down there was a video room, which isn't being used yet, and two toilets, so it could have been worse.

The Mackintosh house next door is absolutely fine, which is a relief."

Graham Revill was left cursing his luck after the floor of The Wedgwood pub, in Abington Street, was waterlogged only a week after he had taken over as landlord.

He said: "We have been doing the place up since we moved in so this has come as a bit of a blow to say the least.

"Fortunately we acted quickly and it didn't take long to get most of the water off the floor. The carpet will need washing and drying out but there is no extensive damage to the bar or seating areas."

George's Takeaway, in Kettering Road, Northampton, also had its basement flooded.

Owner Ibrahim Has said: "The heavy rain started and water began rising in the cellar through a hole in the floor. At one point it was three feet deep."