http://www.jstor.org/sici?sici=0026-7961(197701)40%3A1%3C91%3ADAICCP%3E2.0.CO%3B2-8&cookieSet=1
Does an irrevocable credit constitute payment?
Maran Road Saw Mill v. Austin Taylor & Co
1975 1 Lloyd's Rep 156
It includes a courts position with discussion what happens when the actual merchant bank opening the credit does not pay.