We've upgraded our trailer as we have to carry two passengers to now.
The Burley is an old style and is very well used. One of the threaded bolts that holds the seat up is missing and I'm guessing you can improvise something from your spares box or get something from B&Q that will do the job.
Despite its age it's still quite functional or will be when the bolt is replaced.
Asking for a large bottle of Leffe Blonde and a bottle of Duvel, you'll have to collect from West Midlands, not far from Cannock Chase if you want it