This depends mainly on what the written statement of employment particulars and your employment contract say.
You must be given a written statement within one month of starting work. The written statement should say clearly whether or not the handbook and staff rules are contractually binding and form part of the contract of employment. (From April 2020, the law is set to change, so that your employer will be required to give you the written statement and any important staff rules from the first day of your job.)
Even if the written statement says nothing about whether the handbook is part of your contract, some of the rules in it may still be contractually binding in some cases.
Your employment contract also contains some important implied terms, including a general duty to obey all reasonable management instructions and a duty on both sides not to breach the duty of trust and confidence in every employment relationship.
Any rule or procedure that is part of your conditions of employment is a contract term and cannot be changed by either side without agreement. Where a trade union is recognised in the workplace, the change will normally be negotiated through collective bargaining.
Stay up to date with the TUC and get the latest news and get early access.