Aer Lingus on BA

Just looking at a May/June break transatlantic break and noticed that it's cheaper to book Aer Lingus J class on BA website than it is directly on EI.

As flights start from London no positioning required. Can pick BA for London Dublin sector for extra tier points and business class.

Have been looking for this on the BA website but unable to find it, no Aer Lingus code share show up

I suppose it depends on dates/destination. I was looking at Boston and New York.