Three men, who built a nail bomb and planted it in a block of flats where Portuguese families lived and near where a 14-month-old toddler was playing, were last night starting jail terms totalling 15½ years.

Three men, who built a nail bomb and planted it in a block of flats where Portuguese families lived and near where a 14-month-old toddler was playing, were last night starting jail terms totalling 15½ years.

The attack was aimed at terrorising foreigners, a judge ruled yesterday as he increased their sentences by 18 months each for racial aggravation.

Nails, broken glass and screws packed around rockets were shrapnel designed to harm, Judge Peter Jacobs said, adding: “It is a nail bomb.”

The three men - Sinclair Maynard, 27, of George Trollop Road, Watton, Daniel Taylor, 22, of Market Street, Shipdham, and Paul Lusher, 23, of Griston Road, Watton - planted the crude make-shift bomb on the first floor landing of the Old Brewery block of flats at Watton, where around 20 Portuguese lived, in August last year.

Taylor balanced the bomb on a banister opposite a door behind which a 14-month-old toddler played.

The baby's mother, Anna Alves, and her mother, half-brother, half-sister and fiancé were also in the flat, along with 12 others who were in different parts of the building. The explosion caused metal and glass to fly out and a baby's pushchair to catch fire, but no one was injured.

Photographs of a “wall of death” in Lusher's bedroom - which included posters of the Tavistock Square bus bombing, Osama Bin Laden, a man being hanged and dismembered limbs - were shown to Judge Jacobs who said they were “worrying”.

The men had previously pleaded guilty to a charge under the Explosives Act of causing an explosion endangering life or causing serious injury, which carries a maximum life sentence.

Maynard and Lusher were sent to jail for five years each, with Taylor, who was described as “extremely bright”, receiving an extra six months for previous convictions, including burglary.

The Norwich Crown Court trial was to decide if the crime was racially motivated, and how great the threat posed by the device had been.

Defence lawyers for the three men argued it was a stupid prank that had gone “horribly” wrong and the men had never intended to harm anyone.

But Judge Jacobs picked up on a throw-away comment by Taylor who told the court that he had not knocked on the door of the flat to warn residents of the imminent explosion because if they opened the door they might be harmed.

Judge Jacobs said: “It strikes me as a rather telling answer, which was given spontaneously, and reflects his state of mind at the time. He thought the blast would be powerful enough to propel the nails with enough force to hurt somebody.”

He said the argument put forward by the defence that the shrapnel was just ballast to weigh down the device made no sense.

He said that if the aim was to cause a bang it did not need weighting, and that glass was too light to have any value as ballast anyway, adding: “The items put in it were obviously sharp”.

And he rejected arguments that the three had placed the bomb in the building because it was opposite the police station and they wanted to annoy the police, or that they thought it would make a louder noise inside because of the echo.

“I have no hesitation that this building was targeted to give vent to some frustration against the foreign workers,” he said.

“This is something that affects the community as a whole - indeed it put the community in terror.

“Obviously there are degrees of terror but an explosion like this is designed to put the community in fear and in this particular case it succeeded,” he said.

All three defendants told the court that they had been stupid, but had only planted the bomb because they had been bored.