2002 Building Regs state it is not allowed to discharge a waste into a hopper. Only exception I believe is as a direct replacement for an exisitng hopper arrangement
Wondered how long it would take someone to quote from the textbooks.
This is the real world.
You carry on bossing into your castiron stack.
I'll be on the next job by the time you've finished.
And customer will be happy as I won't have ripped him with pointless labour and £40 charge for boss.
Seriously, anyone who can be bothered to waste time bossing into a castiron stack when there's an easier and still perfectly legal alternative can't be that busy with work.