thanks, I have found this on the UKBA website:
http://www.ukba.homeoffice.gov.uk/worki ... s/#header2
Your sponsor's reporting duties
Your sponsor must report to us:
if you do not turn up for your first day at work;
if you are absent from work for more than 10 working days without the sponsor's permission;
if your contract of employment (including if you resign or are dismissed) or if any registration you need to work in the United Kingdom (such as with a governing body) is ended;
if they stop sponsoring you for any other reason, for example, if you move in to an immigration category that does not need sponsorship;if there are any significant changes in your circumstances, for example, a change of job or salary (but not job title or annual pay rise);
any suspicions they may have that you are breaking the conditions of your permission to stay.
You must give your sponsor all the information they need to be able to meet the duties above. If you do not, we may investigate the sponsor and take action against you both.
If you are an employer, see all the sponsorship duties including record keeping, reporting, and compliance in the employers and sponsor section.
What to do if you think your sponsor is not complying with their duties
If you think you sponsor is not complying with their duties or has given false information to us about you, you must tell us your concerns.
You should contact the Intelligence Unit or sponsor licensing unit whose details you can find on the right side of this page to report any abuse of the points-based system.