I find Arco are not the cheapest but have top quality and a good choice for all work clothes and boots. Let him pick his own for the sake of the peace though. Be warned though they do have some of the designer ones, which are quite pricey and not that much better. Try to guide him to comfort and practicality if you can.
If he likes the Terra ones I can recommend them, they are really good.
Thermo...just been reading their site and they do indeed sound the dogs bo**ocks. I appreciate quality and don't mind paying for it. Just out of curiosity what are we talking for an off the peg (as opposed to custommade) pair of boots. I live in Manchester so luckily it isn't that far for me to go there.