Hey kricklewoodfarm. Totally understandable; the best I can offer up is our themer's guide, which goes into some depth on this end. Check it out: http://tri.be/support/documentation/events-calendar-themers-guide/.
Hope that helps. Unfortunately I can't go into much greater depth here on the dot-org forum, but if you ever go PRO (where we can provide a deeper level of support than we can for free users), our dedicated support staff at the tri.be forums can do their best to help get any lingering issues sorted.
Thanks!