The right-hand drawing may now be dressed as a Celtic cavalryman, but originates as a *Roman* cavalryman (on p. 24 of Peter Connolly's book "Tiberius Claudius Maximus - The Cavalryman", published in 1988 by Oxford University Press, (c) Peter Connolly 1988).
The reconstructed (Roman) saddle may be found on p. 31 of the same book, (or from p. 235 of Connolly's "Greece and Rome at War", published in 1998 by Greenhill Books, (c) Peter Connolly 1981, 1998.)