I thought I'd help myself with the crotch curves by copying them off the black bengaline trousers and transferring onto this pattern. This involved altering the back pattern piece quite a bit but just changing the curve slightly on the front.
I made the front waistband longer as I am flatter at the front but swaybacked.
I then partly constructed the trousers and tried them on to see if I could manage without the back zip. They have a fixed front waistband, a centre back zip and a back elastic casing to two parts either side of the zip. This seemed overkill and I wanted to avoid the zip if possible.
Overall they were too long in the waist and I didn't like the way the back casing would have an angle in it (from my alteration). I marked either side of 1 inch elastic with a sliver of soap (I prefer soap to chalk on dark fabrics).
Here's what that looks like.
The white lines are drawn above and below the elastic belt and are broadly where I want the waistband to be. The front has the waistband attached but flipped up.
The back includes the casing but flipped up.
The lines are a bit wonky as I'm doing this for myself whilst wearing them, so I will smooth them out to something sensible.
So this time I will trim off from the top of the waist, but that will affect the pockets. They are large with a big opening so they will still be usable once shortened, but it may be best to shorten the tissue in a different place for next time.
I'll show you what they look like once I have done that and finished them properly.