Thanks for all the replies and suggestions, I looked, looked and looked and tried on. There are some lovely shirts out there and I'm sure perhaps wonderfully effective, but in the end I decided to go for 'cheap' so have just bought one from Decathlon. For me, hiking shirts are not something I would wear every day, only when I'm hiking, so I decided that £30 would be my maximum spend. I actually spent £22. The shirt may be fine or rubbish, I'll find out on my next walk.