I have a problem. I overstayed my uk tourist visa for about 10 months and decided to return voluntarily. However during my exit in February 2016, I did not meet any immigration officer at the Heathrow Terminal 3 before boarding the plane. I just went through the normal boarding process everyone went through without getting my passport stamped as an overstayer. Now I have gained admission to study a master's program in September in the uk and would like to make an application for a visa at the uk embassy In my home country. Is there any likelihood that the visa officer might know I overstayed my first visa even though nothing shows in my passport? Any help please? Thank you. Note my passport was never expired so it's the same passport I came back with.
The UK does not directly inspect passports on exit, so it is no surprise that you have no passport stamp. Instead, since April 2015, they have collected information from airline passenger manifests. They therefore almost certainly know about your overstay, in which case if you fail to mention it in your application you will almost certainly be banned for deception.