In reply to all:
I had another play around with it at lunch and this time it did remember the setting. One difference was that I left it on longer, and then left it longer between pressing the other switch.
One thing which I hadn't done before was flick the same switch on and off a few times without any real pause. What happened with this today, was the light flicked between the different lighting styles (warm, white and blue?) with each on/off.
If I left it 30 seconds between each on/off then the next time I pressed it it retained the same light as before.
So it's quite possible that the light has some kind of setting (not detailed in the manual) which allows you to change the light settings without the remote they supply. And if that's the case then it is probable that when we have been testing it, we have been moving between the two switches too quickly which has then altered the setting, rather than reset back to default which was my presumption.
So maybe in "normal" use where you would turn it on, leave it for a while and then turn off later it will work properly. I'll have another play with it later to see if that is the case...