A research study into prisoners received into prisons in England and Wales under Indeterminate Sentences for Public Protection (IPP) between April 2005 and March 2006 found that 46 IPPs had been given for rape or attempted rape. Of these 46, two had a tariff of under two years; 21 had a tariff of two years to less than four years; and 20 had a four year plus tariff (tariff details were not provided for the remaining three).
These figures have been drawn from administrative IT systems and data returns from prison establishments which, as with any large scale recording system, are subject to possible errors with data entry and processing.