Just to update the story....
Broadband availability checker shows 25/5 (low) speed estimate
Actual speed is usually 11/1 with occasional drops to 2/1 requiring a modem restart

After long hold periods on phone to ISP, multiple call backs, and visits from BTOR the ISP has accepted that what I've got at 11/1 is as good as it gets. BTOR engineer advised that the property is approx 2.4 Km from the cabinet and 800 m from the DP.

So as I understand it the speed is what would be expected for the distance from the cabinet and the DSL speed checker is estimating high as it only measures to the DP and ignores the last hop to the property.

ISP agreed that I was not achieving the estimates and after some negotiation downgraded my service from 80/20 to 40/10. This allowed a new service package to be applied to my account and a price adjustment.

I still have an unlocked Huawei HG612 in place and await the introduction of G.Inp.
Now how do I find out when it might be applied to my cabinet?

It helps if your cab is a Huawei as currently that's the one that G.INP has been applied to. No evidence of G.INP having been applied to any ECI cabs as far as I know.

Which exchange are you on?

From studying the band profile on the HG612 modem the cabinet is a Huawei.
Although at times when the speed was rubbish I thought I was connected to a green wheelie bin.
I'm on NIKTS exchange.