Thank you for your reply nereid. Funnily enough I have upgraded to 1.5.1 now and it appears to work in the way that I 'thought' it worked previously. For example, any horse would do for the upgrade from Sturgian Brigand to Sturgian Hardened Brigand, including (I think) Sumpters. For 1.5.0, I think you are right, as I was able to upgrade using a Midlands Palfrey. Thank you for you help tho.