When Bill Oddie was on the show with Kate, it had a certain 'Beauty & the Beast' appeal for me in terms of presenting the show. Personally I'd keep Chris and loose Kate. I'd imagine they probably demand, far too much of the program's budget, is given over to make-up and full length mirrors. I'd Definately get rid of Gordon - he drives me nuts. I've always been a big fan of Chris Packham. I think he's extremely well informed and a first class photographer. I find his enthusiasm endearing, and, I actually find the 'once a week format' better for me.
Now... as for Peter and Katie Price, there must be something in the forum rules about mentioning them in posts? They offer a very good case, in favour of human culling