I was privileged to work with Mark since 1987. His leadership on reintroductions led to two sets IUCN Guidelines, which, largely because of him, have become accepted best-practice worldwide. All those who worked with him found it to be stimulating and enjoyable. He always put conservation first, not his own ambitions. His underlying cheerfulness could lift the spirits of a meeting. Above all, Mark was a gentleman. Like many others, I am hugely indebted to him, and shall greatly miss him.