The distributor made minor changes to secure a 15 certificate for the UK theatrical release. The UK theatrical cut is the same as the International Cut except for the torture scene, which was replaced with the PG-13 version to secure a 15 certificate. In the PG-13 version, clamps are attached to the chair. In the International Cut, they're attached to spikes which are stabbed into the victim's legs. The uncut International Cut was released with an 18 certificate on video.
This censored UK version was also released theatrically in Ireland with a 15A certificate. The extended torture scene didn't affect the certificate on video, and the uncut International Cut was also released with a 15 certificate in Ireland (cinema and video certification systems are different in Ireland - a 15A at the cinema is equivalent to a 15 on video).