Confidence: It's likely to be this, but I can't be certain.
Notes: "Previously listed as Leptocerus nigronervosus in Mosely (1939) and Athripsodes nigronervosus in Macan (1973). A large dark species with conspicuously darker veins." (Barnard and Ross 2012). The fore wing length is given as 8-10mm for males and 10-13mm for females. This insect was the same proportions as Oecetis ochracea, fore wings approx 12mm, quite big. The dark veining fits the bill.