Great Gatsby trousers

My brother's friend is organising a Great Gatsby party. He wanted plus fours to wear to it. Now, I didn't research plus fours or plus twos or any of that jazz, although I know I should have.
We took an old pair of my mother's tweedy pants.

Took in the waist, cut off the legs, and added a band below the knee.

My brother's under-knee is 32cm in diameter.

I found very appropriate buttons (I think!)

Can't wait til he tries them on.
And I hope to be roped in to dress some of his friends too :)
... I have a feeling I overlapped the button part towards the front when it should be towards the back. So now, with that in mind, I'll undertake some historical research; check if those buttons are as appropriate as I like to think. It was nice to know I could pull it off sewing-wise.