Most of the missing items were small pieces kept in a storeroom belonging to one of the museum’s collections.
None had recently been on public display, and they were kept primarily for academic and research purposes.
The museum is taking legal action against the dismissed member of staff and the alleged theft is also being investigated by the police.
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Paul Holcroft, managing director at HR consultancy Croner, said employers should undertake a thorough investigation if they suspect an employee may be stealing.
He said: “When trust is broken, it can leave you feeling betrayed. However, it’s important not to let emotions cloud your judgement and always follow the correct procedures. You should carry out a full investigation before making any decision.
“This should include looking over CCTV footage, meeting witnesses and speaking to the employee in question to get a full understanding of the situation.
“If there is concrete evidence linking an employee to theft then there could be appropriate grounds for dismissal.”
Holcroft said following any investigation, employers should offer a formal hearing with a chance to appeal.
He said: “The employee should be given written notice of a disciplinary hearing, warning them that there is evidence linking them to the alleged theft and the potential outcomes, up to and including dismissal.
“All employees facing dismissal should be given the option to appeal if they feel the decision is unjust, so make sure to set a clear time frame and process for them to do so.
“To ensure fairness throughout the process, the person who conducted the initial investigation should not lead the disciplinary hearing. This gives the opportunity for someone else to hear and examine the evidence and statements from both parties and decide."
