I was following Charles Lewton-Brain's step by step instructions from his book "Hinges and Hinge-Based Catches".
This is a great book to add to any jeweller's reference library!
"This book analyzes hinges and hinge-like mechanisms in a manner never done before in a single volume. It has become a classic for jewelry making. Along with history, generics, classes of hinges, guiding principles, sections include: design, tube making, hinge pins (force-fit, riveted, upset, tapered, cotter type, tubing, square, threaded, stud), hinge types (basic, thick-walled, locket, bracelet, box, block, cold-rolled, tab, cast and milled), lubrication, catch systems, hidden, alternative, cast hinges and solving design problems. Good index and table of contents. Covers more information about hinges than any book in English. 112 pages, over 200 line drawings."
There are many steps involved, documented below by Glendine Gogel.
I did not follow the last suggestion of soldering the catch button while shut and therefore it soldered on a bit crooked, I will be re-soldering...