Half a century ago, The Proceedings of the London Mathematical Society published W. N. Bailey’s influential paper Identities of the Rogers–Ramanujan type [16]. The main result therein, which was inspired by Rogers’ second proof of the Rogers– Ramanujan identities [49] (and also [48, 28, 15]), is what is now known as Bailey’s lemma. To celebrate the occasion of the lemma’s fiftieth birthday we p...