By around 1982/3, levels had dropped drastically & the casual/regular canings were starting to become legend and folk-lore. Most schools seemed to be reserving caning purely for the anti-social or deliberate rule-flouters. At which point, political and social pressures started to enter the fray and we first started to hear about the rights of the child.
And, Nelly, regarding lateness-there was simply a space reserved for them at the back of morning assembly. They filed in with the Catholics, Jews, Dissenters & other religions.
The only people asking questions might be your form Master, so the simple thing was to seek him out straight after assembly & before first lesson and apologise for your missing registration. As long as you either accepted responsibility for getting up late or didn’t invent a patently stupid reason such as leaves on the line at Surbiton(in another county!), you were OK.