‘Eton Blue’ (which is rather more green than blue) appeared no later than the early 19th century to identify Eton sportsmen on the river and the cricket field. The colour was also adopted by the University of Cambridge for the Boat Race against Oxford in 1836, and they have kept it ever since.
The traditional colour remained in use at Eton for a hundred years, but various pressures, financial and military, broke the link with the past, and now a pale blue (‘baby blue’) is often used by Eton sportsmen and others. There are moves afoot to re-adopt a distinctive colour, although these will take time to complete.
The colour shown* on this page, which has HTML hexadecimal code #a0d1ca, is a compromise – part-way between a pale blue and the traditional colour. The traditional colour is Pantone 7464C.
[* The colour may not display correctly on some users’ screens. One way of checking whether colours are displaying correctly on your screen is to click here, and see whether you agree with the names of the colours on that page. If you do not, it may be because your screen is not displaying the latter correctly.]