If you are successfully offered this position, you will go through a series of pre-employment checks, including:
identity, nationality (single or dual) or immigration status, employment history going back 3 continuous years, and unspent criminal record check (known as Disclosure and Barring Service)
To be successfully appointed to this role you will need to undergo Baseline Personnel Security Standard checks.
There are no nationality or residency restrictions, although if you have resided outside of the UK within the last 3 years, further checks may be required.
There are other criteria and check required for BPSS, and throughout the recruitment process, you will be asked questions about your security clearance eligibility such as, but not limited to, country of residence and nationality.