I recieved an email from Hilton on Saturday... it reads as so:

Dear Mr. Neilson,

Thank you very much for your email and let me thank you for your loyalty in Hilton HHonors membership program.

Please note, that reservations made though British Airwaves are not entitled for the benefits of Hilton HHonors points and benefits. We will be glad to provide you with all the benefits of your Diamond membership whenever you’ll make the reservation directly through your app or on the Hilton webpage with your HHonors account.

Please let us know in case of further assistance or any other requests.

We are looking forward to see you in Prague!

Kind Regards

XXX XXXX
Executive Reception

Looks as though they will not honour however i have booked nonetheless and will ask the question at check in - fingers crossed.