I have had to confront this issue in the last few days. I knew it was an issue, and I used to have disagreements with Bill who used to look after books that WEC actually published. But we have used a number of publishers to produce and distribute WEC books over the years. Norman Grubb was almost entirely published by Lutterworth Press. This Is That, an account of the Congo Revival of the early 1950s, was published by WEC in 1954, and reissued as The Spirit of Revival by Christian Focus in 2000. The Briefings series is published by Authentic Media. Helen Roseveare has been published successively by Lutterworth, Hodder & Stoughton, Bethany House, and now Christian Focus. And is Operation World a WEC book? There's a can of worms! Its publication every few years is a major worldwide publishing event, and it has always been too big a project for WEC Publications, although the 1993 5th edition had a WEC imprinted edition with a WEC ISBN number. It has been published almost from the start by STL, but it comes deep from the heart of WEC, and WECers rightly own it as our own.
So there's no easy answer. In the web shop you will find books published by a wide variety of publishers, but they are almost all by WEC authors or about WEC people or WEC work (like We Dance Because We Cannot Fly about Betel). Bringing the World to Your Church has been published by WEC but is not by a WEC author or about WEC work - it's one of the exceptions. But we want to bless people and get people passionate for world mission and the kingdom of God, so look out for more books to join the ranks of WEC books.