Not nearly as dated as, say,
Sandra or
Patricia. Or
Tamsin or
Lisa!
I like both
Alice and
Alison, though I'd never be able to use
Alison because of my late MIL's late sister, who lives on in infamy. And I've used
Alice for a cat, very successfully - I don't think
Alison is remotely feline, or animally in general. For humans, it is very pretty and straightforward.
As for
Allison, it's probably one of the early lnfns. And the spelling regularly floors me, just like
Hillary instead of
Hilary. And, now I come to think of it,
Allan instead of
Alan. But they all look so much tidier with a single L.
Ooh, just remembered: a friend's father was named Phillipus! Not sure if the mistake was his parents' or the clerk who wrote it down. And when they had a son, there was a lot of discussion about whether to name him
Philippus or Phillipus, and she argued vehemently in favour of
Philippus (she was learning Latin at the time and loving it) but she lost, and still shakes her head sadly whenever she writes her brother's name.