Sovereigns parade

[wtf2015]

DS1 decided he wanted to join the military and has been at Sandhurst since January. His commissioning parade is in December and I have no idea what to wear. I’m a middle- aged, horsey, country bumpkin of a single mum. My ex will be there with his new, blonde, slim, glamorous London wife. Would a tweed suit be acceptable?

Yes

It's daytime smart/Sunday Best/posh garden party sort of thing, not full on wedding dressy-smart

So a suit in a good fabric sounds good choice

Is it an outdoorsy thing (nice coat, gloves & scarf) or is it inside or both? Good fabric suit?

The Parade itself is outdoors, always, whatever the weather (including pissing with rain) and as you're looking at a December one it's damned cold on that parade ground. Add thermals!! And think about a not too ostentatious hat (too big spoils view of others) but with enough brim to keep rain off face.

It'll finish in time for lunch, so you need to check with DC if you'll be invited to any form of reception, and what it'll be like.

A good coat and warm boots would also be a good choice

Yes, focus on a coat in one of your best colours, and a hat, and boots.
Enjoy!