i'd say at that amount of money try everything you can, even things quite a bit below budget, but also a bit above too (not much point in setting an arbitrary limit of £1800 if, say, your perfect guitar can be had for £1900)...
i'd be trying all those boutique guys like melancon, rahbek, suhr, etc., also fender custom shop, G&L... also stuff like musicman if it doesn't have to be the exact strat shape...
can you get a tyler for £1800? i really liked one of those i tried, but it was £2700 ( :lol: ) and also HSS rather than SSS... but if he does a more vintage strat, it would presumably be worth a try...
if you have very precise specs, and you're willing to wait, a custom-build would be worth considering too... :)
EDIT: i would also say, take your time, there's no rush. when you're spending that amount of money you want to be sure it's what you want...