Winchester Crown Court has found Allan Grimson, a former Royal Navy Petty Officer, guilty of historic sexual offences after a four-week trial. Grimson, who is already serving a life sentence for two murders in Portsmouth, was remanded to prison and is due to be sentenced at the same court on 6 November.
Charges, victims and verdict
The jury returned guilty verdicts on all counts brought against Grimson. The indictment included 11 counts of indecent assault, one count of rape and one count of taking an indecent photograph of a child. The alleged offending took place between 1994 and 1999. Four victims were named in the proceedings; they were aged between 14 and 19 at the times of the alleged offences.
| Item | Number |
|---|---|
| Total counts | 13 |
| Indecent assault | 11 |
| Rape | 1 |
| Indecent photograph | 1 |
Context of previous convictions
Grimson is serving a life sentence for the murders of two young men in Portsmouth in the late 1990s. He had been considered for parole and preparations were under way for a move to open conditions when he was charged in February 2025 with the historic sexual offences now before the court. The trial at Winchester examined allegations spanning several years when the defendant served in the Royal Navy.
Court observations and prosecution case
During the hearing, the prosecution described a pattern of behaviour that included deception and manipulation. The court heard that Grimson had, during a 1999 murder investigation, volunteered the names of the four people who later gave evidence in this trial. The judge described a particular feature of the case as an “oddity”.
“The oddity about this case, was that it was Grimson himself who had first volunteered the names of the four victims during the course of a 1999 murder investigation,”
The prosecution argued that the defendant had used his position of authority in the Navy — including a role as an instructor at a fire school — to target younger servicemen. Three of the victims were said to have been met in that environment; the fourth was met outside the naval community. The prosecution characterised Grimson’s conduct as involving “deception, lies, manipulation and then cover up.”
- Verdict: guilty on all 13 counts after a four-week trial at Winchester Crown Court.
- Sentencing: scheduled for 6 November at Winchester Crown Court.
- Defendant status: currently serving a life sentence for two murders; remanded following conviction.
The conviction closes this phase of the historic allegations brought against the defendant. Sentencing next month will determine any additional custodial measures to be imposed in respect of these offences. The case will remain a point of considerable local and service interest given the defendant’s former role in the Royal Navy and the fact the trial was heard in Winchester.
