Unnecessarily patronising, but a pretty good description of my system. Except that I had just the bare minimum of fall so I'm glad I did it myself, having seen the results of professional work (including two uphill drainage pipe runs).Because you’re not a pro’ and have little experience. Drains ere great fun when they are a foot deep, in stable ground, no need for IC’s, plenty of fall, and lots of room to work.
Not patronising at all. You haven't lived until you have just severed the water main (to a block of three busy households) and no stop tap in sight, late in the working day.Unnecessarily patronising
Drainage seems like one of the most profitable parts of building to me
Drainage seems like one of the most profitable parts of building to me. The materials cost almost nothing, and it's not that big a deal. I replaced every underground pipe and fitting here a few years ago. All by hand, all without a digger. Plus I know it's all very precisely fitted, all edges bevelled and deburred, I doubt it would have been done anything like as carefully if someone else had done it. The 1990s pipes I removed looked like they'd been cut with an axe, and a couple of lengths sloped backwards. All done by professionals no doubt.
Why?stay well away from old tar covered cables and lead pipes.
The building regs can be downloaded for free. They're very clearly written, almost everything you need to know is in there...Poster # 21,
In all your digging activities there's no mention of your water testing new drainage or having your excavations inspected by BCO.
Perhaps inconvenient details are irrelevancies for such a busy chap?
Whatever, I would encourage anyone with even half a brain to follow the Bldg. Regs.

You make an outrageous claim that previous solicitors "simply didn't care"
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local