A children's charity has urged youngsters to report abuse sooner in the wake of the Jimmy Savile scandal.
A poll conducted by the NSPCC found that fewer than one in five would report abuse concerns as soon as they arose.
The charity's own data shows that almost half of people who contact its helpline have waited over a month to get in touch, with some waiting much longer.
A six-week television campaign begins on Monday, explaining how the public can report abuse.
Peter Watt, director of the NSPCC's helpline, said: "Child sexual abuse is not a problem that died with Jimmy Savile. It is a problem that continues today, with children across the UK suffering at the hands of a minority of adults.
"Whilst the uplift in reports of abuse and new figures indicating that people are more willing to speak out is very welcome, it's also clear that people are still waiting for that elusive certainty before taking action.
"People clearly have the desire to act but are unsure how or when to do it.
"The truth is you will probably never be certain because of the hidden nature of abuse, especially sexual abuse.
"And the poll also shows that 59% of people are not confident that they could spot the signs if a child they knew was being sexually abused."
Concerns have been raised that reporting abuse immediately, could result in families being needlessly investigated.
On Sky News's Sunrise programme, presenter Eamonn Holmes asked the NSPCC's head of child protection, Chris Cloke, if there could be any repercussions from informing on their friends or family.
Mr Cloke said: "We know that people are concerned that if they get it wrong, it could back fire on them. But we say put yourself in the place of a child and what it's like if you are a child and are being harmed.
"If that goes on for a long time, it can also have repercussions over a long time."
Savile's record of abuse is thought to be unprecedented - with 28 alleged victims being boys and girls aged under 10. However, many of the TV star's accusers only came forward after his death.
Psychologist Dr Linda Papadopoulos said: "Jimmy Savile was allowed to abuse in part because people were not certain what they were seeing was abuse, and in part because the children themselves were not listened to or believed.
"It's vital that people listen to what children are saying, and that they report concerns immediately even if they are not certain."
:: Anyone who has concerns about a child or wants advice can contact the NSPCC for free 24 hours a day, by calling 0808 800 5000, or emailing email@example.com