Any other preferences besides warmish neutral and open? Assuming based on currency indicated, that they’ll need to be available in the UK. Also, what amp/source will you be running them from?
Hmm…It may be possible to find something like a HEX V2, LCD-2 PF or Classic occasionally fall into that range if you don’t mind buying used and keeping an eye out for a good deal. I liked the Dan Clark Aeon Open X from Drop, but not sure how different it is from the Aeon Open RT, which would be in range. Not sure what availability looks like for you. These may be more warm than neutral than you’re looking for, but I’m blanking on much else in that range that would be on the warmer side of neutral.