The man suspected of stabbing to death a heavily pregnant woman in broad daylight walked away “as cool as a cucumber” and shrugged his shoulders when confronted by police, witnesses said.

Claire Wilson, 22, was seven months pregnant when she was stabbed in the back in a “completely random” attack as she walked to work in the centre of Grimsby on Sunday.

A 53-year-old man was arrested by police officers who were sitting in traffic just yards away.

Tributes have poured in today as friends and relatives gathered at the scene to add to the growing shrine devoted to Miss Wilson, who was expecting a baby girl she had planned to call April.

Detective Superintendent Christine Kelk of Humberside Police said that there was no obvious motive for the attack, and said: “The tragic thing about this is that it was completely random. She was walking to work locally on her own at the time.

“It would appear that she has been followed by the man, who then stabs her in the back with a knife.”

Miss Wilson’s friend, Dave Stembridge, 18, said: “She just didn’t deserve it. She was one of the greatest people anyone would want to meet.

“She was just amazing. She’s going to be missed so much. It’s just not fair.”

Lara Cole, 16, said Miss Wilson and her boyfriend, identified locally as Adam Kennard, 23, were excitedly awaiting the birth of their first child.

“She was lovely,” she said. “She was really funny. She always put a smile on everyone’s face. It’s really sad.”

A pub landlord, who asked not to be named, said that a man had come into his bar shouting that a woman had been stabbed. He said that the man, along with a DJ called Rick from the pub, then chased a suspect up the street.

He said: “Rick said to him ‘Why have you just stabbed a young girl like that?’ He said he just shrugged his shoulders. Rick said he had walked down the road as cool as a cucumber, as though he hadn’t done anything.”

The landlord said that a group of people were comforting Miss Wilson, who was lying outside a travel firm in Grimsby town centre with a black-handled knife in the middle of her back.

“I could see it was serious,” he said.

She had been on her way to work at Pizza Hut when the attack happened shortly after 4pm on Sunday. Colleagues said they feared something was wrong when Miss Wilson, who was never late, failed to turn up for work.

Colleagues said they had walked past a white forensic tent on their way to work, but hadn’t realised its significance until later.

One said: “When we realised, it was just horrible. I’m still expecting her to come through the door.”

Miss Wilson’s boyfriend, Mr Kennard, was heard shouting and screaming on the scene shortly after the attack. Today he spent nearly half an hour on the spot where his girlfriend had died with a group of family and friends, and left a “Baby Girl” balloon as a tribute.

Friends said that the couple had been together for many years and had returned to Grimsby after spending some time living in Italy. Miss Wilson had worked at Pizza Hut for two years, where she was described as a tremendous, bubbly personality.

Ms Kelk of Humberside Police said: “She was from a fairly extensive family, she had lots of people who loved her and supported her and she was about to embark on a new stage of her life, giving birth in a matter of months.”

Witnesses said today that police officers had reported that doctors had fought to save Miss Wilson’s baby, but Ms Kelk could only confirm today that the unborn child had also died as a result of the attack.

One card left at the scene today read: “Baby April. You would have been the most loved baby in the world. Take care of your mum for us.”

Police are appealing for witnesses to the attack, but said that the area was likely to have been quiet due to heavy rain at the time of the incident.

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