A paranoid schizophrenic who killed a former banker from Putney in a vicious knife attack has had his minimum sentence cut by half, it has emerged.

John Barrett repeatedly stabbed 50-year-old Denis Finnegan, of Dryburgh Road, with a kitchen knife after ambushing him as he cycled through Richmond Park.

He was sentenced to life imprisonment at the Old Bailey in March after pleading guilty to manslaughter on the grounds of diminished responsibility and he is now being treated at Broadmoor hospital. Sentencing him, Judge Anthony Scott-Gall said he would have to serve at least 15-and-a-half years before he would be considered for release on licence.

But it is understood the judge reviewed the tariff and brought the case back to court for a private hearing within 28 days of sentencing him. He cut the tariff to seven years under the so-called "slip rule".

Mr Finnegan's brother John said nobody from the Crown Prosecution Service (CPS) had been in touch to explain why the sentence had been cut. He said the judge should not have changed his mind about the sentence he passed.

A spokesman for the CPS said: "We have every sympathy for Mr Finnegan's family who we were in touch with during the prosecution.When a sentence is reviewed it is normal practice for the courts to inform police so they can attend as first point of contact for victims' families.We had no reason to believe this had not happened. THere seems to have been a breakdown in communication."