In the episode The Mysterious Moles, a very different Colonel Wilcox briefly appears. Unlike the one that appears in the rest of the series this one is an air force colonel (you can see the air force pin on his uniform) and had a different voice.
Someone looking exactly like the Air Force Colonel Wilcox appears unnamed in Professor Goodfellow's G.E.E.C. talking to a pilot on how the test of the new jet could be dangerous.
There were no 'new' Army Class A Dress Green Uniforms issued after 2010. They were formally decommissioned in 2015.