Three Burghley titles, four Barbury CIC3* victories, 2,113 British Eventing points — it's hard to keep a tally of the achievements of Mark and Rosemary Barlow's 16-year-old grey gelding Avebury. Andrew Nicholson's ride certainly made his mark on the eventing world, and following the announcement that he was put down yesterday (6 September), we celebrate his trophy-clad career in pictures