Elachiptera

Or austriaca - there is a discussion https://www.diptera.info/forum/viewthread.php?forum_id=5&thread_id=53106 which may help to separate these two.

Thanks Tony, I am familiar with the diptera.info discussion and others and you're probably right about it being austriaca however I cling hopefully to the pair of orbital bristles.  I have emailed John and Barbara Ismay so I hope they will be able to shed some light...