HIDDY touches on something LTN-Phobia has raised in the past -- cheap tier point runs (or any non-BA spend) being used for high levels of status.

BA could run a seperate BA-only tier, which would allow SGL and GGL at say 1000 and 2000 tier points per year (for minimum of 2 years), but only look at tp earned on BA eligible flights (perhaps JV ones too)

They would keep Silver and Gold as One World levels as normal.

This would allow BA to "Enhance" Gold and Silver, without annoying their frequent travellers.

(P.S. Flights in J and F shouldn't earn any tier points either. Passengers in these cabins are already pampered enough)