Now for a worst railway journey contender
Personally I'm struggling to think of one, so I'll go back to enjoying listening to the suggestions of others again...
I have a similar problem, most of my regular journeys are nice ones so it's difficult to choose a journey for this thread. Many possibilities have already been mentioned by others, but none of them really qualify as bad enough to be 'worst journey' for me.
Don't get me wrong, there's some routes that are incredibly tedious such as Shrewsbury to Gobowen. I just can't find anything to really enjoy about that bit of line! I do agree with the person who commented on the A55 ruining the views on the North Wales Coast, but equally some of the engineering involved is fascinating. I think it was in the Llanfairfechan and Penmaenmawr areas that the road gets interesting, in terms of how much it has to dive up and around the rest of the infrastructure and through tunnels etc.
I'd also agree on Birmingham to Wolverhampton, it's not an exciting route in terms of scenery but there are some bits of interest. The Wolverhampton end always feels the worst bit of that route personally, but I wouldn't say it's the UK worst route.
I'm also not a fan of some of the routes around South London, there's something about the Brixton and Balham areas I just don't like. Mind you, I always feel 'off' in Shoreditch and the surrounding area, there's a weird vibe over there and I don't know what it is. The only thing I know for sure is that when I'm in the area, I can't get out of there quick enough!
Yet other parts of London are brilliant. I haven't been to London for a good while, definitely feeling the need to return soon!
The Penarth branch I don't like much, same for Barry Island, there's some weird vibe in both areas and after encountering a violent person near Cogan earlier in the year I'd rather stay well clear of the area! This was in the middle of the day, not a late-night mission! Merthyr Tydfil has a weird vibe to it as well, my best experience there was a meal in the Tesco cafe many months back during a big cycling session from Risca to Cardiff via Route 4 and Route 8!
So in short, without scouring the memory for all the unpleasant journeys I've ever made, there's a lot that I've done that I don't like but I can't honestly say any of them are the worst in the country!