Graham Byrne and David Crimmins are both well acquainted with the seaside town of Dún Laoghaire. They first came to know each other there more than two decades ago through Tesco, the global grocery giant whose Irish headquarters is based in the town. At the time, Crimmins was helping to launch Tesco’s credit card in Ireland before going on to roll out other personal finance products. Byrne, then working with GE Capital, partnered with Tesco to provide complementary credit protection products. So it is perhaps fitting that I meet them along the seafront, where, over coffee, Byrne and Crimmins explain…