The UK Ancestry visa entitles a Commonwealth citizen, with a grandparent born in the UK, to gain entry to the UK to take up or seek employment and eventually settle in the UK.

How do I qualify for this kind of visa/permit?

You must be a Commonwealth citizen
You are 17 years of age or older
You must be able to prove that you have a grandparent born in the United Kingdom, Channel Islands or Isle of Man. This grandparent can be on either side of your family
A person can also apply for the ancestry visa if they are adopted, or if the parent through whom they are claiming ancestry is an adopted child; You must intend to work and be able to work; You must be able to support and accommodate yourself and any dependants without using public funds

How do I apply and do I need entry clearance?

Application is made through the British Embassy in Bangkok.
You must obtain an entry clearance for United Kingdom ancestry before you travel to the United Kingdom. However, applicants will under certain circumstances be allowed to change their visa status to an ancestry permit holder from within the United Kingdom.

Siam Firm Inter Law will be able to assist you in both instances.

Some Rules and Restrictions on Holder of UK Ancestry Visa:

The visa is granted for a period of four years.
You do not need a work permit and can work without restriction.
You are also required to intend to work when coming to the UK.
You can leave and enter the UK multiple times.
You have no recourse to public funds. You are allowed to apply for a dependency visa for a dependant who wishes to accompany you to the UK.

Does this visa lead to indefinite leave to remain?

Yes, one month prior to the expiry date of the visa at the end of the four years, the holder may apply for the status of 'indefinite leave to remain'. In order to be eligible to apply for indefinite leave to remain, the applicant must, if required, be able to provide evidence that they have indeed been working during the four years of their visa. In addition, the applicant must not have spent on average more than 90 days per year outside the UK, during the four year period, the year commencing on the date on which the actual visa was endorsed in the passport. If the applicant does not, for some reason, meet the criteria required to apply for the ILR, then an application may be submitted for the extension of the Ancestry Visa status.

After 4 years continuous stay in the UK on an Ancestry visa you may apply for permanent residency.