Reasons in favour of disclosure:

1 -  By giving details voluntarily will be seen as an attempt to start afresh and will count in your favour, by showing that you are being open and honest from the start.

2 -  If you give the actual details yourself, it could improve your credibility and show you in a positive light, before information is supplied by other people.

3 -  You will not have the on-going fear that the employer will find out about it later on.