Checking references are important, it is strongly advisable to have references on the person before he or she takes up any position in the organisation. Especially in situations where the employee will be working either with children or vulnerable adults, in this case references should be received as assessed before the person takes up any employment.

It is usual that at least one of the required references is obtained from the candidate’s most recent employer. However the present employer should not be contacted until the candidate has been made a formal, written offer of the post (the offer should be conditional on the satisfactory completion of pre-employment checks) and has told their employer, unless the candidate has given their permission for the prospective employer to do so prior.
 

Source: NCVO