In Northern Ireland it replaces the Disqualification from Working with Children (DWC) List, the Unsuitable Persons List (UP List) and the Disqualification from Working with Vulnerable Adults (DWVA) List

A separate but aligned scheme will be introduced in Scotland next year and anyone barred in any part of the UK will also be barred from working with children and vulnerable adults anywhere else.

The Scottish scheme places the onus on the employer or organisation to make sure vetting is carried out - individuals will not be held responsible.

The scheme in England, Wales and Northern Ireland launches on 12 October 2009 and will be phased in. Individuals will be able to apply to register from July 2010. Registration and the checking of people's status will be mandatory from November 2010.

Who will run it?

Parliament has established a statutory body to take decisions on who should be barred, called the Independent Safeguarding Authority (ISA).

This has a board of 10 members with expertise in safeguarding, chaired by Sir Roger Singleton, and more than 200 caseworkers/decision makers.

People can apply for vetting with the ISA via the website.

Who has to apply?

Anyone who works or applies to work with children or vulnerable adults - either in a paid or voluntary capacity.

So the scheme covers teachers, private tutors and sports coaches but also people such as doctors and nurses, opticians and dentists and taxi drivers on education contracts.

I volunteer at my child's sports club - do I have to apply?

Yes, anyone working or volunteering on behalf of a third party organisation ¿ for example a sports club or a charity ¿ who has frequent or intensive access to children or vulnerable adults will have to be registered with the scheme. For volunteers, registration is free.

However, the VBS does not cover personal or family relationships, so parents making informal arrangements to give lifts to children will not have to be vetted.

If you volunteer with more than one club you only need to be registered once - the club can then check you have a registration - as long as you give your consent.

I occasionally help with reading at a school: do they mean me?

The checks will be necessary for anyone who has contact regularly, intensively or overnight - defined as once a month, three times or more in a period of 30 days, or between the hours of 2am and 6am.

I am hosting an exchange student for my son's school: do I have to apply?

Yes, this is counted as a "regulated activity" and it will be a criminal offence not to be registered with the ISA. You will not have to pay the fee, however.

This affects the person nominally providing the accommodation and food. But other adult members of the household, or visitors, will not have to be vetted.

I'm a private person not an employer as such - could I check on a nanny?

Yes.

How will it work - can anyone check my ISA registration?

No, all information held by the ISA about individual applications and cases will be secure.

Prospective employers are only able to check if the person is ISA-registered if they have the explicit consent of the individual, along with a unique reference number and other personal data.

A feature of the scheme is that the status of individuals will be continuously updated on receipt of new information, such as convictions or referrals from employers.

Does it replace CRB checks?

No. What ISA registration shows is that there is no known reason why the applicant should not work with children or vulnerable adults.

It does not check for malpractice or all criminal convictions if they are not relevant. Employers concerned about wider issues will still need to obtain an Enhanced CRB check.

So who and what is deemed unsuitable?

Anyone who engages in conduct that endangers a child or vulnerable adult, or is likely to, by causing physical, sexual, emotional or financial harm.

This includes having sexual material relating to children or depicting sexual violence against people, or conduct of a sexual nature involving a child or vulnerable adult if the ISA thinks it is inappropriate.

Some practices will result in automatic barring. Others are deemed to represent a very probable risk of harm to children or vulnerable adults but not necessarily in every conceivable case - so people will get a chance to make representations to the ISA.

Is there an appeal against barring?

Yes, via the Upper Tribunal.

So would this have stopped Ian Huntley?

This would depend on whether information was passed on to the correct authorities or shared properly between police forces.

One of the issues with the Huntley case was that although he had been arrested on several counts of rape and sexual assault against young girls in Humberside, and even charged with the rape of one, records on him were deleted from the system.

The rape charge was eventually dropped and even though he had confessed to "having sex with a girl under 16", the girl then said she did not want to prosecute and Huntley was not even cautioned. A caution would have flagged him up on police systems. In addition, one force had also not passed on to others that Huntley had gone by an alias.

The ISA says that a key strength of the new scheme is that "it has access to non-conviction information from different sources when building a view of an individual's unsuitability to work with children or vulnerable adults".

The ISA poses the question this way: "Would the new vetting service bar someone like Ian Huntley?"

Its answer is: "One of the key features of the Huntley case was that, although his behaviour had caused concern to a number of agencies, and on a number of different occasions, no single organisation had access to a full picture or had put together those aspects of the picture that they had."