I got a UK visa last month and visited London for a week. It was my first visit to the United Kingdom. I checked-in online when I was leaving the country and entered my visa number as an additional document. I was surprised after security checks in the airport, there is no passport control and I will not get a "leave stamp" in the passport.
How do I check if my visa information was passed to immigration service? Since I had an electronic check-in via a third-party airline company website, I can not be 100% sure that the company passed the information to theUK immigration services or their website works 100% correctly.
I already read the answer from here Left UK without passing through Immigration, why?
In order to avoid misunderstandings, I am not curious about WHY I do not have leave stamp, my question is:
WHERE to check if my departure has been registered?
The proposed duplicate How to fill out and apply for Subject Access Request (SAR)? and its answer appears to be obsolete because "The Data Protection Act 1998 has been replaced by the General Data Protection Regulation (GDPR) and the Data Protection Act 2018. For the latest guidance on data protection law, please see our Guide to the GDPR."