While Mr Weenie is adamant that Eenie will NOT be making an appearance on a bike/trailer while in infancy, surely there's no harm in looking? Besides, some of them are purely cargo ones...
To my shock, what I've discovered is a huge expensive array of options. For under £200 you can get a rather swanky bright yellow option with five-point harnesses for up to two children.
I've also stumbled across the frankly disturbing idea of 'doggy joggers'. Yes, trailers so that even the most pampered of puppies can avoid getting their paws dirty while still enjoying the scenery.
What I also found was AtoB, a sustainable transport mag that has a fairly comprehensive list of the available trailers.