At least three of the attacks in the district are being linked to a gang dubbed the Pie Robbers, and others – which police say are not connected – have been remarkably similar.

Some of the violence has been shocking. Victims have had bleach and petrol poured over them, been beaten with crowbars and clubs, stabbed and threatened with guns.

Detective Insp Ashley Hewitt has led some of the investigations. "The level of violence used has been extreme when you look at what the offenders are trying to achieve and that is of concern to us," he said.

Extra officers have been drafted in from the West Yorkshire organised crime squad to help Calderdale detectives with their investigations into the "pie robberies", which began on Christmas Eve.

Detective Insp Hewitt said: "When we have a high number of crimes like this, it's not unusual for us to draw on resources from elsewhere to help our inquiries.

"Many of these type of crimes are targeted. What I would say to people who handle large amounts of cash or own a business, is to look at what security procedures are in place and if they need any help, advice or information then please get in touch. Crime prevention officers can arrange to see you and review your security."

On Christmas Eve, club stewardess Sheila Haigh was attacked with a wooden club as she opened up at the Stone Chair Variety Club, Shelf. Three masked men burst into the flat above the club and threatened her husband, Les, with a wrench. One robber held him captive while the other two went downstairs and demanded cash. They escaped with £3,000.

On January 12, raiders armed with crowbars, burst into a house at Wakefield Road, Lightcliffe, and robbed guests at a dinner party. One guest was hit over the head with a crowbar as he tried to protect his partner.

Nine days later, a pie maker was doused in bleach by masked raiders who hit him with a hammer and threatened to cut off his fingers.

Lincoln Stead was working at the Crusty Pie Company, Shelf, when three men carrying hammers and crowbars burst in.

Detectives linked it with the previous two, plus another two raids in Bradford, making meat pies the bizarre connection.

The Bradford home of the owners of the Crusty Pie Company, Diane Congreve and Richard Edhouse, was raided twice in 2007, and the owner of Stobart's pie bakery based in Low Moor, Bradford, hosted the dinner party in Lightcliffe.

The robbery at Stone Chair Variety Club puzzled police until the Courier revealed the club once ordered a batch of pies from Stobart's.

Two attacks with chilling similarities to those carried out by the Pie Robbers, have happened in the past month but detectives are not linking them.

On February 25, a woman was confronted by two masked men at her home in Mount Tabor, Halifax, demanding to be shown to the safe. She was frogmarched through the house before being doused in petrol and told she would be set alight.