Compression socks.

Thank you all. Finding socks to fit DH is a nightmare at the best of times with his size 13/14 feet! I'll have a good browse before buying and make sure we are getting the right size.

We always wear compression socks on a flight over three hours as it does help you to avoid a DVT. Also getting up frequently, drinking water, avoiding alcohol etc are also advisable. We've been given socks on long haul flights in the past but have our own and just pop them on before boarding. Have a good flight.

I wouldn't bother if you have no obvious contraindications, just take a small dose dissolvable Aspirin or half a normal size one before you go.
Have a good time.

They will all conform to standards if you buy them from a reputable source

Amazon sell them, I think you will find that they are all pretty much the same, just select the correct size.