The number of individuals convicted since 1978 under the Prevention of Terrorism (Temporary Provisions) Acts 1974 and 1976 is available on the Home Office website in "Statistics on the Operation of the Prevention of Terrorism Legislation, Great Britain". This publication details detentions under this Act and outcomes including statistics on individuals found guilty. It is available quarterly through the 'archive' page back to 1979.
The Terrorism Act 2000 came into force on
These detail arrests under this Act and under other legislation where the investigation is considered terrorist related and the outcomes to those arrests, including convictions.
For this period, there were 41 Terrorism Act convictions. There were also 183 convictions under other legislation.
In addition to the aforementioned, statistics on the number of convictions in significant terrorist cases are collated for 2007 and 2008. In 2007, 37 individuals were convicted in 15 significant terrorist cases. 21 of those individuals pleaded guilty. So far in 2008, 21 people have been convicted in seven significant terrorist cases. Of these 21, 10 individuals pleaded guilty.
Figures are complied from police records and are subject to change as cases go through the system. The Home Office is currently working with the police to review how terrorism statistics are collated.