Roberts, now 78, was handed a life sentence in 1966. His 30-year minimum tariff expired 18 years ago.
A man who was at the scene of the murder of three unarmed policemen has told ITV News it is a "disgrace" that one of the men responsible for their murders is being released from prison.
Glen Hazell, who was 11, was playing with friends in Shepherd's Bush when Harry Roberts and two associates opened fire on the officers in 1966.
The Parole Board today announced that Roberts, who was handed a life sentence, will be released after serving 48 years, a decision that has sparked fury among police groups.
"I don't think he should be allowed anywhere near the public...it's a disgrace," he told ITV News Senior Correspondent Emma Murphy.
A public memorial service for Alice Gross will be held next month, her family have announced, as they paid tribute to the support of local people in Hanwell.
ITV News Reporter Sejal Karia reports:
The parents of Alice Gross have described their devastation at the "appalling circumstances" of her death.
In a statement released on the day of their daughter's funeral, Jose Gross and Rosalind Hodgkiss said Alice was "so spirited, so present, so vital and so full of promise".
“We find it almost impossible to understand what has happened and that we have to say goodbye to her.
"We want Alice’s funeral to focus on the joy of Alice’s life and the joy of having known her."
They also thanked the community of Hanwell for their support during their ordeal, saying it has "touched them very deeply".
Three more nurseries have joined in the protest against Barnet council's plans for budget cuts.
Barnet Unison, which represents St Margret's, Hampden Way and Brook Hill, are opposing the council's proposals that the three nurseries should merge to save money.
They have followed in the footsteps of Moss Hall Nursery School and launched their own petition online.
Moss Hall campaigners have continued to gain support with their petition now standing at over 2,400 signatures.
A council meeting is due to be held on October 28 at 7pm to decide plans for the future.