Thanks to a post from someone else, my favourite's now a transparent plastic mini Ashforth feeder. As long as you have some roof space above your top bars. You need to cut a bee-width entrance slot out of the middle of one edge of a top bar - or just use for this purpose one narrower bar the same depth as your other bars, to which you pin at each end a short strip of narrower wood, leaving a gap in the middle. (This gap to be covered when feeder not in use). Drilling holes in the bar surely would work well too. The feeder then just sits on top and is easy also to refill from its other, bee-free, end without lots of bees joining in. - Am thinking I'll also be able to lay any broken pieces of honey comb etc. in the feeder to be fed back to the colony/cleaned out if needed.