Firstly please forgive any ignorance I display from here on in!
I have an Ormiston Flute which I found in some gear I picked up at a car boot sale of all places! I thought nothing of it until a friend said they were good flutes and so have been trying to find out anything I can about it for the last few weeks. It has four keys. Is dark wood with silver. It has G Ormiston and a number on it and I am desperatley trying to find out how to firstly get it valued and secondly sell it. I have visited another website/forum (session) and they suggested here might be a good place…Anyone… 
Here’s the maker’s website: http://www.ormistonflutes.co.uk/
That’ll give you an idea about what you’ve got.
What’s the number?
I have an Ormiston like the one you describe and it’s a fine flute – though I bet I paid more for mine ! 
Here’s some information about the man who makes them and what they are:
http://www.ormistonflutes.co.uk
Doublecheck with George to see if he has anyone looking, and then maybe see if this fellow https://www.irishflutestore.com/newsite/index.php? wants to consign it. Alternatively you can sell it in the “Used Instruments Forum” here, or list it on eBay. The one thing that would be good to know is if it’s in good working order, and how old it is. Mine’s something like #323 and I got it new probably 15 years ago if that helps you “age” yours at all. I think I paid around $1300 for it back then. Anyway, from what I’ve seen a four-key in good shape might get you as much as $1000, as the market’s not very good now and the Ormiston name isn’t as big. But he makes nice instruments, so you’re good in the quality category. NB: Be careful with it as far as handling, assembling, and blowing into it go if it hasn’t been used for a while (and is dried out) – a cracked or bunged-up one is worth much less!
Good luck!
Thanks all for the replies. Looks like it was a bit of a lucky find then! The number on it is 487 I think. Cheers all! 
Forgot to say, it’s in great condition but I’ll be sure to avoid the temptation of blowing into it!!
cquick sold his 4-key Ormiston for $750 on the Used Instrument Formum: https://forums.chiffandfipple.com/t/fs-copley-ormiston-lehart-flutes-rose-whistle/70932/1
He had been attempting to sell that flute for over a year. 
Best of Luck!