Primary Six pupils Ho Ka-chun and Tsang Tsz-hung, of the Tai Kok Tsui school, described him as a 'funny' person who liked to play games with pupils in class.

'I was surprised,' said a Primary Six pupil at Pegasus Philip Wong Kin Hang Christian Primary School cum Junior Secondary School, who was in Mr Sewar's reading class last year.

Mr Sewar quit the Pegasus school on Friday after details of his background - which he claims he was never asked about in a year in the city - came to light on the internet.

He has insisted his conviction was for a minor, non-sexual offence. The matter has sparked a debate over the feasibility of background checks on teachers from abroad and the balance between privacy and protecting children.

Parents are divided over the resignation of Mr Sewar, who is on permanent leave of absence from the Catholic priesthood in the US.

Phoebe Fong Yeung Oi-yan, mother of a nine-year-old who was taught by the American, said her daughter did not understand why he had disappeared from the school until she explained. She said Mr Sewar's departure was the only option and the incident had been a life lesson for her daughter.

Another mother, Mrs Yeung, said he should be given a second chance. 'Everyone has done something wrong [in their life]. Why don't we give him a chance? It's a matter of many years ago,' Mrs Yeung said.

Ms Yu, the mother of a Primary Three boy at Carmel Leung Sing Tak School, said schools should not employ teachers even if they had not been convicted of, but only charged with, a sex offence against a child.

'Even if there's a small chance that they offended in the past, the school should not have them,' she said. Her son was never taught by Mr Sewar, nor did Ms Yu know the former teacher.

Apple Chung, mother of a pupil at the Tai Kok Tsui school, said the school should take more responsibility in protecting children.

'The school should have studied a teacher's background thoroughly before employing him,' she said.