Santa:
Not quite: The minimum height of an unmarked bridge in the UK is 5 metres (we went metric 40 odd years ago guys). 5 metres converts to 16 feet and 4.85 inches which is near enough for jazz, but 5/32 of an inch would be serious in many situations.
No, that’s still “not quite” correct. The Chapter 4 Traffic Signs Manual (effectively, the legal “bible” for road signs) states that 5.03m is the figure to be used when deciding whether the bridge (or other structure) requires warning signs, not 5.0m
It goes on to specify how the measurement is to be made and the figure on the sign(s) is calculated. There are different methods for imperial and metric measurements (which helps to explain why the metric figure on the signs is sometimes not the direct equivalent of the Imperial figure also displayed). Full details here: tsrgd.co.uk/pdf/tsm/tsm-chapter-04.pdf (page 30-40).