Some further helpful clarification from the guys today.
Our free shipping for all EU orders is now over €150.
However, for small parts, accessories and also some decoders(slow sellers or for older runs), these are shipped from our warranty team in Darlington, or Dublin. This allows us to continue to offer these items, which are not suited to shipping from our main warehouse, which is a large fulfillment operation.
The postage on those orders are charged based on the appropriate Royal Mail tarriff, which the system will apply at the checkout.