IWAF - thanks for that - all very useful. Yes, I am trying to build an argument to present to my partner as to why I need another bike...

I do have a mountain bike that I could use but frankly, I think they just look a bit silly on London streets and are made for bouncing along the North and South Downs. Cross bike sounds like the perfect compromise!

I know trailers are probably a bit more stable but they absolutely terrify me unless on a traffic free bike path - it's bad enough that people in cars don't seem to see me half the time but a bike trailer just isn't anywhere near theri eyeline (or am I wrong about that).