A baby’s nanny was jailed for 10 months today after she deliberately made an 18-month-old boy fall three feet to the floor.

Gemma Grogan, 29, of Sandy, picked up the crying toddler – from Royston – and bounced him up and down on his bottom.

The assault was recorded on CCTV installed by the child’s parents in their home, St Albans Crown Court heard.

Prosecutor Oliver Weetch said the boy was taken to Addenbrooke’s Hospital in Cambridge, where tests were carried out. He was uninjured.

Grogan was recorded on August 3 last year, with the boy on a changing mat in the nursery.

She initially punched him on the leg, and he began to cry. She then slapped him and made him stand, at which point she took his hand, encouraged him to the edge of the table and let him fall.

Three weeks earlier, on July 19, she had slapped his legs and handled him roughly while changing him.

Grogan, of The Avenue in Sandy, appeared for sentence having pleaded guilty to two charges of child cruelty. She was of previous good character.

In a statement to the court, the boy’s mother – who had employed Grogan for eight months – said: “I don’t understand why she acted as she did. It is particularly hard when there is no explanation. We treated her fairly.”

The husband and wife now feel they can’t trust anybody to look after their child again.

Minal Raj, defending Grogan, said she and her husband had been having fertility difficulties.

“She has experienced anxiety and depression and is at a loss to explain her behaviour,” she said.

“She has worked as a nanny for 11 years and is deeply remorseful, extremely sorry and devastated.

“Bizarrely, she was aware of the overt CCTV in the house.”

Recorder Jeffrey Yearwood told Grogan: “There can be no more trusting job that any parent can give to someone else beyond that of caring for their child – the younger the child, the greater the trust.”

He added that her fertility disappointment could not excuse her behaviour.

Jailing her, he said: “Despite your good character and character references, this court would be failing in its duty and sending out wrong message if the offences were not marked by immediate custody.”

Grogan must pay costs and £800 compensation, as well as a £140 victim surcharge, and has been banned from contacting the family indefinitely.