The payment clause is lawful and behaves like pay-when-paid
It never says the words, and the money still does not move until somebody upstream has been paid.
What's happening?
The contract never says paid when paid. It does not have to. Long payment periods, application windows a day wide, due dates pegged to certificates and events you cannot see, each one lawful on its own. Stacked together they produce the same result the banned words used to: your money waits until money has arrived from above, and the clause that does it never shows its face.
The Construction Act made true pay-when-paid clauses generally ineffective years ago, with a narrow exception around upstream insolvency, and every drafter knows it. So the delay gets built lawfully instead. That distinction matters, because the two kinds of term need different answers: terms the Act would strike down anyway can simply be flagged, while terms that are lawful but loaded only move one way, by being negotiated before signature.
If you are reading this on a live contract, the immediate question is what the Act and the served notices actually require of this cycle, and some of that can still be tested. But the durable fix is at the table: the next order with this counterparty priced with the clause understood, pushed on the terms that can move, and walked away from where they will not.
The solution
The clause's real machinery read, and what this cycle still allows.