The BBC seemed to have a habit of poaching ITN newscasters in the 1980s didn't they? Anna, Selina, and in 1986 they poached both Pamela Armstrong and Martyn Lewis and Peter Sissons in 1989. I guess ITN took Julia Somerville from the BBC and Mark Austin but he was nowhere near high profile at that time. Can anyone think of any others that made the swap?
Pamela Armstrong, like Katie Derham, didn't move to the Beeb to be a newsreader, she moved to do a daytime show, the imaginatively titled Pamela Armstrong. She did later do Breakfast Time but, like Derham, she was presumably looking to move on from newsreading.
Julia Somerville was a very high profile move at the time, she was one of the senior presenters on BBC News at the time, having fronted the Nine O'Clock News for four years, I think it was a bit of a rancorous departure as well. Martyn Lewis was apparently hired because the Beeb specifically did research to find housewives' favourite newsreader. Peter Sissons moved over from Channel Four News to do Question Time specifically, which when Robin Day left was a very high profile role, but he asked if he could do newsreading as well to keep his oar in with the news on a regular basis.
A lot of these moves were quite minor in the grand scheme of things. Up until the nineties there weren't many opportunities in TV news, just the Beeb or ITN, and there weren't many news programmes either, so if you were ambitious and wanted to get on you would often have to look at the other side for potential openings. I think the general feeling has always been that most people would generally gravitate to the Beeb - even in the seventies and eighties, when ITN were considered superior by every margin, there was a prestige about the Beeb that made it very appealing.