In reply to The Lemming:
I have taken a look at all the recommendations and read various reviews google threw up about them. Some of the reviews also suggested alternatives which the author's thought the reader may be interested in. And this sent me down an interesting voyage of discovery.
If anybody is still interested I finally chose a 'wild horse' which was not even on my radar, but got some excellent reviews. So I took a punt and went for a Marshall Kilburn. I placed an order and it arrived today giving me a chance to test it in my company van with all the background noise that it creates, including woo-woo noises.
http://www.pcmag.com/article2/0,2817,2490249,00.asp
I have to say that I was mightily impressed with the sound quality. Its battery life should see me through a few shifts and its fookin loud. Some of the reviews put it as the loudest bluetooth speaker in its class and capable of knocking out 100 dellybells at a distance of 1 meter. It is audibly superior to my cheap Phillips speaker in all respects.
Now I realise that you should never compare proverbial apples with oranges but I gave it a sound test by putting it up against my Sonos Play 5 speaker. Obviously the Sonos speaker sounded better however my new bluetooth speaker was almost as good. Its sound quality was somewhere between my Sonos Play 1 and Play 5.
It looks sexy too.