Will you get stopped or questions asked at Heathrow if you overstay a Tourist Visa?

As far as I am aware there is no explicit visa check when leaving the country. Would the airline ticketing person check if your visa is expired?

You have to scan the boarding pass before security. Does this process automatically check if one has overstayed the visa.

Basically the question is if you have overstayed for a tourist visa, is there a real chance that you would get stopped when you are leaving the country. I know it would be a problem when you apply for a future visa, but would there be any issues when you leave the country.

Basically the question is if you have overstayed for a tourist visa, is there a real chance that you would get stopped when you are leaving the country.

No. However UKVI will receive the information from the airlines of the date you departed, so will be fully aware.