Howorth served for twenty-three years with the Royal Army Ordnance Corps with postings to Austria, Japan, Tripoli in Libya, Stonecutters Island in Hong Kong and various United Kingdom bases.

[1] On 26 October 1981, police received warnings that bombs on a busy shopping street in central London would explode within thirty minutes.

A booby-trapped improvised explosive device, planted by the IRA, was discovered in the basement toilet of a Wimpy restaurant on Oxford Street.

In 1985, IRA volunteers Paul Kavanagh and Thomas Quigley,[3] both from Belfast, were convicted of Howorth's murder, along with other attacks, including the Chelsea Barracks nail bombing in September 1981, and each was given five life sentences with a minimum tariff of thirty-five years.

[4] Mr Justice Girvan rejected the challenge, finding that the wisdom or fairness of the Northern Ireland Sentencing Act 1998, which established the early release scheme, was not a matter for the court and commenting "History will be the ultimate judge".