Thank you. Employers generally have the right to choose who they employ and can make such decisions based on a relatively wide range of factors. There could be a number of reasons why one candidate is chosen in preference to others or why someone is not given a job, even if they are generally considered to be the best or most suitable candidate. In fact, it is generally lawful for the employer to use whatever factors they feel are relevant and appropriate in the circumstances to arrive at that decision.
The only requirement in law is that the employer’s decision is not based on discriminatory grounds. This means that they should not base their decision on what are known as ‘protected characteristics’. These include things like gender, race, religion, age, disability, sexual orientation, etc. If their decision is based on or linked to any of these characteristics, there will be a potential case of discrimination and the affected person can potentially take this further. However, in the absence of any discriminatory reasons, the employer will rarely be acting unlawfully and will have the general power to be selective over whom it employs, even if it this generally appears to be unfair.
In terms of trying to find out what they have on you, you can always approach them and make a subject access request under the Data Protection Act 1998 for them to disclose any personal data they hold about you. Whilst legally they should disclose that, if it is something unofficial and only a handful of people know about it and there is no other evidence to suggest it exists, they can potentially just say they have nothing on you and simply refuse to disclose it. Without evidence it exists, it would be very difficult to actually take action against them and argue that they are deliberately withholding it, especially as they can destroy it quite easily if necessary.
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