Oh my, what a gorgeous staircase! Are you sure you're not applying a protective finish? Maybe something like Osmo Polyx Oil Raw, which will not affect the current colour and shine much. Do discuss it with your carpenter. And keep some of the leftover wood to try out a finish, if you want to/need to.

Look at the first pic, it's finished with an Osmo Oil https://www.stockwellstairs.co.uk/gallery/

Info about the oil (I promise I don't work for them and I've never used an oil like this, but I thought it might be a good idea for your stairs) https://www.osmouk.com/sitechapter.cfm?chapter=82&page=312

Do you have underfloor heating?

Sorry I should have said it’s getting treated with Osmo 🙈 yes I have under floor heating and unfortunately can’t put real wood down because there isn’t enough clearance for my bifold doors.

I think I'd go for a porcelain stone effect tile in a light beige/ivory or warm grey colour rather than for a wood. Or you need to go for a wood effect that's very different than the oak, but doesn't clash with it. You'd have to get samples and hold them to the stairs, to see if it works.

Or maybe...

That is beautiful (and the view isn’t too bad 😂 ) another vote for a stone effect to let the staircase stand out

Also, there are some lovely LVT floors. They are thin, softer underfoot that tiles, suitable for UFH, and better for acoustics than tiles.

Fantastic extension. And stairs. And view. 🙂 👌

Agree with letting the staircase stand out and not going for a wood-look floor. Love Carolina’s grey-ish ‘stone’ floor suggestion (top foto).

No advice but how beautiful are both the stairs and that stunning view. What part of the country is that? I’m very jealous. A view is priceless

I live in Perthshire , the view is amazing! I’m very lucky x

Thanks everyone, I think a stone look porcelain tile is the way forward. I sent for samples some time ago and I’m loving some of the Quorn stone tiles x

Amazing pictures! Have a look at Bruge from a company called Clay and Rock. We’ve just had this put throughout against old bleached oak beams, so a similar tone. The tiles are large format and look like flagstones, but not to the extreme that some are replicating. Most of the trades onsite couldn’t believe they were not real stone. Colour is a good blend with oak. This is an image from the store, but doesn’t do them justice in fairness.

I second all the above. I have used a lot of Osmo products. Make sure it's the Raw and not the clear. Any oil will react with UV light eventually and darken slightly, but the Raw will remain the most like natural wood. I would not have a wood floor but go for huge large format porcelain with a slight surface texture, or, natural stone, I think the beauty of natural wood needs to be put with something earthy and natural.