More about the stencil...

From Patricia Mullins' The Rocking Horse;

'Occasionally one finds the stencilled words, "PATENTED JAN 29 1880" on the base of some swing stands, notably those of F H Ayres and G & J Lines. Usually, those who patented an invention...indicated that a product was protected by marking it with the patent number and date. (The patent was for the swing stand, invented by an American, Philip Marqua).

Patent 395 actually became void after only three years when the renewal fee was not paid. In this case any patent marking should have been discontinued after 1883, although, according to the British patent office, it is quite possible that the marking may have been used for some time after that date.

Horses bearing this patent stamp on the stand base should, therefore, date from the 1880s.'

Yes! Zaphod is 120 years old.

Apart from his head.