UK Ancestry Visa Extension
If you have a grandparent born in the UK, there are possibilities that you may already meet the requirements of British Citizenship by Descent (from a British parent or a mother or father born in the UK) or British Citizenship Double Descent (from your UK-born grandparent).
If the parent through which you can obtain this Ancestry Visa spent at least 2-3 years in the UK, and you have not yet turned 18 years old (i.e you are younger than 18), then you may be able to Register as British under new UK Immigration rules. Please refer to British Citizenship by Double Descent (PG-UKM2010).
An extension to the Ancestry visa is available (strictly speaking, the visa is re-issued) to a candidate holding an existing and valid Ancestry visa. This occurs at the expiry of an existing Ancestry Visa and happens when you have NOT yet met the UK residency requirements for Indefinite Leave to Remain (ILR).
Strictly speaking, this Ancestry Visa is an Employment category visa. This is because the candidate must demonstrate that they are employable and should make every effort to maintain this during their stay in the UK. It is still a TEMPORARY RESIDENCY visa, but it is formally considered WORK AUTHORISATION.
The Ancestry visa entitles holders to seek employment in any field in the UK for a period of up to five (5) years. After five years, holders may be able to apply for ILR as long as they continue to meet the requirements of their visa and have not travelled outside the UK for longer than the permissible time periods.
No more than 180 whole days absence are allowed in any of the five, four, three or two consecutive 12 month periods. Contractual work travel can normally be excluded from this calculation, but advice should be sought if this to be relied upon.