Caran seem to be confusing 'catch up' with '+1' channels. The latter simply rebroadcast programmes one hour after they've originally been shown, whereas 'catch up' services are 'on demand'.
Any smart TV should have ITV Hub built into it. It's also available on more recent Humax boxes. Otherwise you can simply watch on your PC or laptop:
https://www.itv.com/hub/the-chase-celebrity-special/2a1400a0115
(You'll need to sign up for an account if you're not already registered but it's simple and free).