Watch for my son?

There are many Orient automatic watches that are great and you can never really go wrong with a Seiko, £750 is a hefty budget, you should be able to get a couple of really decent automatics watches for that.

Baltic, Seiko, Christopher Ward

Yeah wow 750 is a healthy budget. You can go Swiss with Tissot or Hamilton. If you want to support your home country, Christopher Ward makes some really nice ones too.

Tissot Gentleman. Look at one in person. The finishing is outstanding; the movement is an upgraded Powermatic 80 and a beautiful all-around watch.

Tissot, Seiko, Baltic, or Lorier

Tissot PRX. Very versatile. Quartz and mechanical available. The quartz ones can be had for under £200 when on sale.

I would go with either a Hamilton khaki or Seiko Alpinist. Honestly there are lots of options in that price range so definitely keep looking.

I'd say go for one of more tool-ish microbrand that uses a workhorse movement.

Go for Traska, Vaer or Nodus. Maen and Lorier for a more classy mid century look.

https://www.maenwatches.com/

These are excellent value for money. I have 2 Manhattan and 1 Brooklyn from Maen.

Great budget you have so many great options a tool watch I would recommend Tissot seastar 1000, dress watch I would go Tissot gentleman that’s the upgrade from Tissot seastar, not sure about Hamilton they’ve problems with dust in the movement but maybe they fixed that, another wonderful dress watch would be grand seiko, not sure about micro brand, but it’s your money and your taste

Something in the Seiko sport or prospex collection would be my take.

What's your son into?

If he's an active/outdoorsy type I'd almost say a hardy quartz tool watch, like the Elliot Brown Holton Pro or Beachmaster Q.

Maybe even a Marathon Steel Navigator? Don't have one yet, but now that they have finally released a steel no date variant, I see one in my future lol.

How old is your son? Wrist size? 1 watch or 2 to cover more situations?

I will be in a similar situation/budget for my turning 18 nephew early next year. An Alpina Startimer or Squale GMT are current favourites - but Certina, Mido and Seiko are also very much in the mix. One left-field option with interesting designs is Ukrainian brand Kleynod, which would be a conversation piece if nothing else and would subtly show support if that sort of thing appeals to him.

Huge thanks for all of the recommendations. This is a great place to start my online research