A man who beat a five-year-old boy to death in a Catford park after the child lost a shoe has had his jail time increased.

Marvyn Iheanacho, 39, watched via videolink from prison as Court of Appeal judges added three years to his 18-year minimum term for the murder of Alex Malcolm.

Lord Justice Treacy, Mr Justice Jay and Mr Justice Warby agreed with Solicitor General Robert Buckland that 18 years was "unduly lenient", and did not adequately reflect the "serious aggravating features" of the case.

Iheanacho, from Hounslow, had denied murdering Alex, the son of his then partner, but was convicted in July after a trial at Woolwich Crown Court and jailed for life.

Witnesses heard a child's fearful voice saying ''sorry'', loud banging and a man screaming about the loss of a shoe during the attack in Mountsfield Park, the trial heard.

Alex suffered head and stomach injuries and died in hospital two days after the attack in November last year.

One of his trainers was later found in the play area by police.

Iheanacho has a string of previous convictions for violent offences, including attacks on ex-partners and robbery.

Increasing the minimum term to 21 years, Lord Justice Treacy announced: "In our judgment the minimum term of 18 years did not adequately reflect the serious aggravating features of this case, which relate not only to the offence itself but also to the offender's past violent criminal conduct."

His previous convictions showed he had a "deeply entrenched streak of violence within him".

Lord Justice Treacy said Iheanacho had attacked a vulnerable young child when he was in a position of trust, and did not get medical assistance for Alex "when it was clear he required urgent care".

The minimum term is the least time an offender has to serve behind bars before becoming eligible to apply for parole - because of time served on remand Iheanacho will have to serve at least 20 years and 119 days.

An NSPCC spokeswoman said: "This was an appalling and grave offence which saw a young child brutally murdered.

"Iheanacho should have been caring for Alex, but instead he violently robbed him of the chance to live a long and happy life.

"Babies and young children are entirely dependent on those who care for them and we all have a duty to look out for their welfare.

"We urge anyone concerned about a child should call the NSPCC Helpline on 0808 800 5000 as it could save a life."