"well similarly I have never met a remainer who will comment on the European court of Human Rights releasing jamie bulger's killers after eight years in children homes - no time spent in a penal institution - despite Michael howard being briefed that the only thing they were interested in was sex and violence and increasing the sentence to fifteen years."

Going by the Wikipedia article

The fifteen year term set by Howard seems to have been overturned by the House of Lords before any appeals to the European Court of Human Rights:

Lord Donaldson criticised Howard's intervention, describing the increased tariff as "institutionalised vengeance ... [by] a politician playing to the gallery." The increased minimum term was overturned in 1997 by the House of Lords that ruled it "unlawful" for the Home Secretary to decide on minimum sentences for young offenders.

The only effect the appeals to the to the European Court of Human Rights seems to have had on their sentence was to trigger a review in the UK:

The European Court case led to the new Lord Chief Justice, Lord Woolf, reviewing the minimum sentence. In October 2000, he recommended the tariff be reduced from ten to eight years, adding that young offender institutions were a "corrosive atmosphere" for the juveniles.

The decision to release them seems to have been made by the Home Secretary following a recommendation by the parole board:

In June 2001, after a six-month review, the parole board ruled the boys were no longer a threat to public safety and could be released as their minimum tariff had expired in February of that year. The Home Secretary David Blunkett approved the decision, and they were released a few weeks later on lifelong licence after serving eight years.