I'd rate that as fairly accurate, in terms of numbers.
Here's the data: The https://www.ons.gov.uk/peoplepopulationandcommunity/crimeandjustice/compendium/focusonviolentcrimeandsexualoffences/yearendingmarch2016/homicideOffice of National Statistics have a chart:
The chart does indeed show a peak rate of 17.9 homicide incidents per 1,000,000 population for the year ending March, 2003.
I'm not sure what deeper conclusions can be drawn. Both the availability of weapons and the likelihood of being prosecuted could have an effect on crime rates.
I would mention that I don't know the political situation in the UK, or what would have caused such a change. It could be the handgun ban.