There are 39 code flags comprising 26 Alphabet 3 substitutes and 10 numerals. Usual overall procedure is 2 alphabet in sequence alternating with a number and finally substitutes. The arrangement should run in an unbroken arch from bow to stern. As well as the aforementioned all usual flags should be flown ie association/club flags Ensign etc.
E, Q, 3, G, 8, Z, 4, W, 6, P, 1, I, Code, T, Y, B, X, 1st Sub, H, 3rd Sub, D, F, 2nd Sub, U, A, O, M, R, 2, J, 0, N, 9, K, 7, V, 5, L, C, S - but that's close enough! Over to you Endymion of Colne! The next number in sequence is question 14.
Buy an ordinary union flag, cut a white sheet to size, cut an appropriate aperture in centre of said sheet, and sew union flag into aperture. Voila! Robert is your Father's Brother!
These people do them The Flag Loft
(although they are not on the web site).
We have always found there prices to be very reasonable and the sewn flags are good quality.