Permissible is perhaps the wrong term - People did them with shitty Molteni sms nylon tops - the question is whether you'll get the stamps (and therefore the pasta/bottle opener gift etc). I can't remember seeing one last year (or ever tbh!?) though if you can convince them it's period correct I think you'll be ok if the rest of your outift/bike is similarly correct.
Permissible is perhaps the wrong term - People did them with shitty Molteni sms nylon tops - the question is whether you'll get the stamps (and therefore the pasta/bottle opener gift etc). I can't remember seeing one last year (or ever tbh!?) though if you can convince them it's period correct I think you'll be ok if the rest of your outift/bike is similarly correct.