Moths are divided by the experts into macro and micro. The best moth identification book (Waring & Townsend - Field Guide to the Moths of Great Britain and Ireland, 2nd edition, 2009) just deals with all the macro-moths. There are illustrations of about 500 micro-moths in another book (Manley - British Moths and Butterflies. A Photographic Guide, 2008), but this is only some of them and identification of the difficult species involves peering at their genitalia through a microscope. There's nothing a true lepidopterist won't do in pursuit of his hobby! And just when you're thinking that micro-moths must all be smaller than macro-moths, then think again! There's a considerable overlap in size.
Anyway, after that rigmarole, here's a picture of a 1.4-cm-long micro-moth (upper photo), rejoicing in the name of the Dark Fruit-tree Tortrix (Pandemis heparana) - and thanks to Danny Arnold for the identification. And there's also a picture of a 1.4-cm-long macro-moth (lower photo), the Purple Bar, which I hadn't caught before.