Are there any services in Sweden that convey first class accommodation but are not reservation compulsory? I can't seem to see any.
You can book a seat for SEK 50 on sj.se.The Krösatågen-branded service from Linkoping to Kalmar isn't reservation compulsory, and had a First Class compartment when I used it a few weeks ago.
The caveat is that every ticket bought seems to have an allocated seat, so good luck actually sitting in First Class. I spent the whole journey on a tip-up seat opposite the conductor's office. He had no explanation for me when I asked either where you could make a reservation or where any unreserved seating was.
Yes you've jogged my memory now - I remember drawing a blank initially but eventually found that it's technically an SJ service.You can book a seat for SEK 50 on sj.se.
(I presume you’re asking because you have a 1st class Interrail pass?)
TÅGAB trains are easiest to find between Stockholm and Kalmar; but they also have a couple of less-than daily routes radiating from Kalmar, including Gothenburg.
It's easy to mix up Swedish towns that begin with Ka, but Tågab's trains usually go to/from Karlstad and/or Kristinehamn.