A brass astral ships clock made by SMITHS used for watch keeping on the bridge with hinged brass bezel and bevelled glass. Large outer ring in minutes, inner ring for hours, red second hand and a slow/fast lever.
This clock comes with a key which we have used to wind it and it ticks for less than 24 hours, we conclude the balance is working ok and it just needs a clean reflected it the price.  We are by no means clock experts though.
Measures 22cm diameter x 10cm deep and weighs 3.5kg.