Chambers does not show the alternative spelling at 8dn as being American, so no indication is required.
'Lancaster' in 26dn is not a 'definition by example' in the accepted sense (as 'Burt Lancaster' would be of 'actor'). Burt is (or was), like Penny and Stuart, an instance of a Lancaster. Azed does not insist on 'for example' or the like being used in such situations - you will find successful Azed competition clues where eg 'West' has been used for MAE, 'Heath' for TED and 'princess' for DI. That said, I don't approve of the practice myself.