"he's having Aloysius carved on it - that's the bear's name"
Sir John Betjeman statue, St. Pancras
Creative Commons AttributionSir John Betjeman statue, St. Pancras - Credit: janson, Flickr
Teddy Bear (1903-5)
Creative Commons AttributionTeddy Bear (1903-5) - Credit: Harry Nguyen, Flickr

Sebastian having his teddy bear at Oxford is said to be based on the actions of the poet John Betjeman who took his bear with him when he went up to Magdalen College in 1925.

Betjeman's teddy bear was called Archibald Ormsby-Gore ('Archie' for short!).

The choice of name is linked to Sebastian's Catholic faith: St Aloysius is a Catholic saint whose feast day is June 21st. It is also the name of a Catholic church in Oxford.