The most recent and comprehensive study of child sexual abuse in Britain undertaken by the University of North London showed that, including any unwanted sexual event that occurred before age 18, over 1 in 2 females and 1 in 4 males had experienced at least one such event.
The most common from of sexual abuse was "flashing" - which accounted for 27% of the experiences - the second most common was "touching" which 23% of the people had suffered. If certain "less serious" forms of abuse are excluded the prevalence figures are 1 in 4 for girls and 1 in 6 for boys. The forms of abuse which more commonly result in prosecution, and which the general public associate with sexual abuse (all forms of rape and forced masturbation) were experienced by 1 in 20 women and 1 in 50 men.
Definitions of what counts as sexual abuse have dramatic impacts on estimates of the prevalence of it.