an odd curlew

doing routine surveys this morning came across an odd looking curlew -- amongst 70 odd curlew it stood out immediately due mainly to its underparts that were distinctly tinged with cinnamon but just as strikingly they had virtually no markings from the streaked breast down to the undertail coverts -- there were on close inspection some fine darker streaks on the flanks and a couple of faint cross bars on the upper rear flanks that were usually hidden by the closed wing; the birds overall plumage tones seemed  slightly more cinnamon than the adjacent curlews and the head pattern also seemed different -- it was into the light and distant so the heavily cropped images are not great but give the impression of the bird - in flight the underwings were strikingly white -- the pristine nature of the wings and tail suggest that it is a juvenile -- interested in any comments -- looking at images on the net could it be a steppe curlew  N a sushkini or could all of these features fall within the range of variation of Eurasian Curlew? is it another Minsmere curlew?