Toni-Ann and the man she thought was her father, Bertram Byfield

Seven-year-old Toni-Ann Byfield, from Birmingham, was shot alongside Bertram Byfield, 41, just over a year ago at a flat in Harlesden, north west London.

Police believe Mr Byfield, a convicted drug dealer, may have been killed over a drug debt.

Scotland Yard said it had received 20 calls from the public after Tuesday's programme and a name was put forward.

Foster family

As a result, it said detectives were now following the new lead in the case.

Det Ch Insp Neil Basu, who is leading the investigation into the murder of Toni-Ann and Mr Byfield, said: "I am pleased with the response we have received from the public following the appeal on Crimewatch.

"We have a number of encouraging leads as a result of the information received."

The appeal was made to coincide with the first anniversary of the murders, committed on 13 September last year.

At the time of her death, Toni-Ann was in the care of Birmingham social services and had been placed with a foster family in the city.

Crack dealers

When the family went on holiday, Toni-Ann was allowed by social services staff in Birmingham to visit Mr Byfield in London.

He was not her biological father, but the child regarded him as such.

Detectives think Mr Byfield had links with a group of crack dealers running cocaine between the UK and Jamaica.

On 13 September, Mr Byfield and Toni-Ann went shopping for her new school uniform and then went to the home of some of his acquaintances.

They left to go back to Mr Byfield's bedsit at 2345 BST after which neighbours heard shots and screams.

The pair were later found dead.

Several people have been arrested in connection with the murders, but no-one has been charged.

A reward of �25,000 is being offered for information that leads to those responsible for the murders.