Well, this is a problem. When submitted to the British Board of Film Censors on initial release, the film ran 113:50. It was passed without cuts. When it was resubmitted for DVD release in the UK, the running time was 108:39 and it was again passed without cuts. Taking into account PAL speed-up, the running time should have been 109:17.
The film has been released on DVD in the UK, and the running time according to the sole review of the disc is 108 minutes. However, the BBFC website also lists a video release submitted after the above which was timed at 97:05. Yet again, passed without cuts. This seems to be the source of the Region 4 version.
In other words, the UK Region 2 is some ten minutes longer than the Region 4. It looks to me as though the Region 4 is missing some footage when the officers have a slideshow of nude photos. Either that or the filmmakers were excessively coy in 1976, which seems very unlikely. As to any other cuts, I have no information.
The Region 2 seems to exhibit the same video problems as the Region 4, but in consideration of the extra footage it seems to be the one to get. It also has the correct aspect ratio of 1.66:1, so that clinches matters.