Backdoor Jobs (in a public health hospital in the UK)

UK - I recently inquired with my previous employer whether or not their were any vacancies or jobs due to be advertised, I was informed that at present their was a job freeze and that this job freeze wouldn't be over until sometime after April 2010. However I would be informed of when they would be advertised and they would welcome an application from me. During my previous time within the organisation I proved myself to be an excellent employee and did leave on very good terms. However a few days later I learned through speaking to another ex-employee that she had approached the same dept who told her she could have a job, no job was advertised and from what this person has said the job given to her had been orginised after a freind of hers in senior management had pulled a few strings? The company is a publich health hospital, and both myself and the individual who has now got are both nurses, this persons employment history is in direct contrast to that of mine, where as she has a high sick rate, criminal conviction for drink driving and less experience. Is it legal for a public company to give a job without first advertising. Many thanks for any advice.
Eddie