I'd forgotten about Aer Lingus' brief flirtation with the 767. I was under the impression that their 747s were somewhat under-utilised throughout their careers, hence the lease-outs but evidently they were all needed at certain times of the year. I admit having this fanciful notion that Aer Lingus might have hung on with 707s for the long-haul fleet until the TriStar or DC10 were ready to go. It could have been risky though if US competitors introduced the 747 between, say, Boston or New York and Dublin. I don't know if this was the case.