The pollution tests are age graded. For pre 75 vehicles the test is visual - ie is it creating it's own smoke cloud. No probes. No graphs.
I said hazards. The vehicle has to be made after 1986 for those to be mandatory. From 1936 most vehicles did come with indicators from new. Many had the old semaphores that admitmittedy are less visible than a hand stuck out of the window!
If that lethal the we're all living on borrowed time!
Charles