Thieves smashed a network of holes through a first-floor office in a botched attempt to break into a jewellery shop below.

Under cover of darkness, the raiders scaled the outside wall of Goldsmiths in Tyrrel Street, in Bradford city centre, and broke through an upstairs window.

They then attacked sections of plasterboard wall in the offices of Simpson Duxbury solicitors.

A senior partner at the firm believed the would-be thieves were acting on old plans showing a staircase and a dumb-waiter connecting their premises with the jewellery shop below.

However, those access point have been sealed for around 20 years.

It seems the thieves also fashioned their entrances into the office walls in an attempt to avoid the alarm system.

However, shortly after 3am yesterday the burglar alarm was triggered and they fled the premises.

Philip Taber, 53, senior partner of the law firm, was called to the scene within minutes of the alarm sounding.

He found three office walls had holes in, but the raiders came unstuck when they attempted to break through a brick wall.

He said: "I appreciated as soon as I got inside there had been a break-in. There were piles of rubble on the floor.

"I went back outside and called 999 because at that point I didn't know if there was still someone inside the building.

"When they arrived, we carried out a full search. There was no-one there but a light on the third floor had been turned on."

He said the burglars were on a hopeless mission.

"The old plans show a staircase connecting our floor with the jewellers downstairs," he said. "This was part of the sales floor when the entire building used to belong to the jewellers.

"But it's been sealed off since we came here 20 years ago, so they have gone to a lot of effort for little reward."

During the break-in, telephone lines and network systems for the computers were severed but not one file had been disturbed.

"All that was moved were two bottles of champagne I'd kept in a cupboard," said Mr Taber. "I have the feeling they were planning to celebrate their success!

"It's inconvenient but we are up and running again. With the help of the staff we've already cleaned up."

Rod Young, 52, manager of Goldsmiths, said: "My first reaction was total shock. I'm appalled at the lengths they've gone to to gain access to our jewellers.

"Years ago every floor was used by the jewellers. When the floors above were sold off, all the entrances were sealed - we are cocooned down here.

"It looks like it was highly organised. I don't think they were opportunists but they were totally wasting their time."

There is a closed circuit television camera mounted in the paved square opposite the end of the building. It is unclear whether the burglars were caught on camera and Mr Young called for tighter security.

He said: "I would like to see better CCTV coverage of this particular street for everyone, for people walking through at night, because it is a desolate place in the early hours."

A police spokesman confirmed that officers attended Simpson Duxbury after reports of a break-in at 3.30am yesterday.