I'm on have both the Amex BA and Barclays Premier which includes Avios.. this allows me to link other credit/debit cards not associated with Avios to earn points. Don't have a specific Barclays Avios card.
Got too many credit cards tbh.. around 15 or so, if i include debit cards... which i use about 3 as my main and the opthers i make random purchases and pay off straight away. This is purely done to increase my credit rating after i got a Default (which i appealed) a long time ago because of a non existent mobile bill