Wow. 20 years. A lot has changed in that time.
Brands
The once-household-names such as JVC, Hitachi, Toshiba, Philips, Grundig, Mitsubishi aren't making their own TVs for the UK market any more. In most cases they've sold the brand name to a 3rd party manufacturer in China, Turkey or Eastern Europe. They make TVs under those brand names, but it's not quality product in the old sense. Other manufacturers are out of the business altogether.
Sony, Samsung, Panasonic and LG are all reasonably safe bets. A couple of these buy their panels from other manufacturers but they still make their own electronics. Sharp sold its TV business to Hisense
Apart from Cello, the brands listed above, and a few high-end products (e.g. B&O, Loewe) then pretty much everything else is a generic product with a badge. This includes but isn't limited to: Alba, Aiwa, Blaupunkt, Bush, Digihome, Dual, Finlux, Goodmans, JMB, Linsar, Logik, Luxor, Memorex, Polaroid, Seiki, Techwood, Technika, Telefunken
Screen Sizes and Resolutions
If your current TV pre-dates digital then you're probably using some sort of external box such as a Freeview recorder or Sky. A new TV will give you the opportunity to add a Freeview tuner for digital TV (it's standard on all TVs now), but what's not standard on some 32" and 40" sets is a Freeview HD Tuner. It's getting less of a problem, but it's still worth double-checking, particularly with the cheaper brands.
At 43" and above you'll start to see a lot of TVs with 4K UHD resolution. This is the new thing. Don't worry about going 4K yet unless you want to subscribe to Sky's HD service or Netflix/Amazon in 4K. It doesn't look likely we're going to get 4K UHD on Freeview in the next few years, and even if we do it will only be one or two channels. After all, we've had HD since Freeview started in 2007, but so far we have little more than a dozen HD channels out of over 100 on Freeview so I wouldn't hold my breath on it yet.
Smart Features
TV is getting more 'internetty'. Smart features abound on TVs, recorders, Blu-ray players, plug-in boxes and USB sticks, your toaster.... okay, I'm kidding about your toaster, but honestly they're everywhere. For that reason don't let it be a big factor in your TV choice.
Having catch-up TV is great, but if there's one thing the last 5 or 6 years of having these features on TVs has taught us it's that once a model gets past 3 years old then support for them from the TV manufacturer gets patchy. That was a big shock to the early adopters. They spent an extra £100-£200 over a non-smart TV when these features fist came out. Now they have a TV where iPlayer and other apps no longer work.
A simple plug-in box or USB stick for £20-£40 will do all that the TV's built-in features will do, and better than that, it won't suffer the same kind of support issues because it's not some bit of custom-written software locked to the TV manufacturers way of working.
Where next?
At this point going in to any further depth beyond what's already been covered by the other respondents is pointless. Time for you to fill in some of your blanks such as what screen size, what you're likely to use it with (Freeview recorder, Sky, Virgin, DVD/Blu-ray), whether you have an external sound system already (and how that connects to yyour current TV), plus any other specific requirements