Not disputing it, but the riots were in May 1989 and it was abolished in 1992 ready for the 1993/4 tax year. You turned eighteen 6 weeks before it was abolished (it had been announced a year earlier)
EDIT: Just checked (lol I wouldn't have been able to in 1989

) and it was legislation passed just before the April 1992 General Election that should the government win (John Major did), would go into force in April 1993.
An interesting (well to me) side-note was that I think April 1992 was the year that I won the Grand National with a horse called....Party Politics

I know it was from the local Ladbrokes as there was no online gambling then. I'll google that in a bit as my memory is a bit cloudy.
EDIT 2: Not that cloudy! I know I got it at 10-1 each way (I think I was done as the starting price when they were off was 14-1) on the 4th April 1992. And I googled it - it was Coral on Old Christchurch Road not Ladbrokes. Gotta love the internet.