Early mobile phone, yours for £225

It's not exactly going to fit your pocket is it? But then, in the days before laptops existed, when nobody even had desktop PCs, I was asked to have a prototype portable computer built as an experiment, to help computer auditors. It worked, and proved it wasn't something we should be doing. It was the size of a large suitcase, and had a full size tape drive. Their spec. Transportable, if you had a car to carry it.

So this is similarly "transportable". User instructions are in the extra. Mobile it might be, but you still need a network to connect to. Not so different from now, in that respect., even if you did have to connect using electric string

And it's "property of the Postmaster General", from the days when post and phones were all handled by the GPO. I imagine it's for use by engineers, but I'd love to know about it.