With such a neutral backdrop (oak floor, grey/white unit, and grey sofa) you could go in any direction with colour. I think you need to understand whether your sofa is a 'warm' grey or a 'cool' grey and then go in the same direction for the colour. To clarify with an example of what I mean... If your sofa is a warm grey a buttermilk or a buttercup yellow would work well. Summer Glow from Fenwick & Tilbrook is a warm yellow. If your sofa is a cool grey a citrus yellow will work better. Concorde, also from Fenwick & Tilbrook, is a good example. I've used yellow here but the principle is the same for any colour. Go with what you fancy but if you want to learn more about colour and its effects I recommend a good book about colour from Karen Haller. It's just out and an excellent read: The Little Book of Colour. Regarding furniture, and in particular a large coffee table - there are plenty available in the shops but if you want something a bit different and not overly expensive I suggest looking in second hand shops for a good quality wooden dining table - if the top is the right size and shape for your room cut the legs down so it's the right height. Depending on the condition of the table you might want to paint it. It would be an opportunity to inject some really bold colour! Good luck with your re-vamp. Don't hesitate to get in touch if you'd like further help.

Really interesting to see some of your thoughts - I looked up the original architect design and found this - so they had the large pane pivoting in the middle, the small panel lifting up at the top, and the bottom fixed section (with the wooden mullions running across it) Does anyone know what the thin section of window at the top is designed for? Is it worth having? It looks a bit weird to me, but I can see from the photos shared it must be typical. How about this really simplified? The bottom sections on the top and middle floors would have to be fixed for building regs. Do you think we have enough flexibility of ventilation just having one huge panel? I don't know much about tilt and turn, can they be this large? (The windows are 1.8m wide, and 2m tall on the middle floor). Or this, simplified but with a few more divisions if important for function? In materials it sounds like plain alu is winning (not the alu clad timber like velfac). This would save us about 10k so not too sad if alu is recommended!! Huge thanks!

Wow, Jonathan thank you for that, some lovely ideas! Unfortunately the builder starts on Tuesday and we have planning permission for the existing plans, but I do appreciate it (and wish I had come here earlier!) The elevated terrace would be lovely, but it's right next to our neighbours house (oddly, the largest windows look directly at the house next door). Our architect is local and doesn't really have opinions about design / aesthetics, and is more at the functional end of the spectrum, so asks what we want and then makes it work technically. Hence needing a little inspiration! I like the simple metal railings that have been shared, and the idea of colour matching to the windows, thank you! A perforated metal screen is very interesting and not something I knew existed. I did a quick google and only found very ornate or very industrial examples - has anyone seen anything like this used in a mid century context? We aren't being slaves to it, and are happy to go modern/MCM. But not a fan of an extremely severe 'industrial' look. The flooring I am completely baffled by - wood is nice but very slippery. Perhaps some sort of external tiles, so it feels like living space? Maybe to match the grey of the windows / railings, or is that too much? Thanks hugely!

I wouldn't worry about changing a house from the 1960's to something more modern. I'm afraid to say that period style ended for me after the Edwardian period which was about 1914 I think. Do whatever you fancy, there are no rules. The tv over the mantle is an american import and quite impractical as the position is often too high for comfortable viewing. Have your tv where ever you desire it depending on sockets, arial reqs. etc If you had an original wooden floor that might be a shame to rip it out but everything else is fair game. We had a 1970's house as our first property and I completely modernised it. No regrets whatsoever..