That £199 ticket is not a bad one.

You need to reserve the outward trip, but the return leg is flexible (take any train within a month). If you don't want any flexibility at all you can get much cheaper, but if you only need flexibility on the return it's a lot cheaper than a fully flex ticket.

It appears in the booking system as a standard class ticket (to get round companies expense policies), but is really first class as it includes free upgrades on each leg. This includes lounge access (for what it's worth, basically nicer waiting rooms).

You get a voucher for a three course meal in the on-board restaurant or at seat dining.

The ticket price includes tube z1-2.

Now for the :

If you go to the East Coast website and try and book this £199 ticket from Edinburgh to London you can book it without a problem. But if you try and book this ticket with the outward from London it shows up but gives you an error if you try and book it!