Thanks all for your input... it might seem like some frivolous concern but having the right mirror is an important part of bike safety. Some of the roads we regularly use have no paved shoulder and knowing if a truck is about to surpass you is very useful.

My partner decided for the topeak mirrors but I'm still undecided... I think I'm going to try a helmet mount mirror, they are cheap so if I don't like it I can just give it to someone else or even dump it.

Cheers