I booked a revenue room (cheapest) and then e-mailed the hotel.

This is the response:

"Greetings from Conrad Hong Kong.

We are pleased to inform you that our Executive Lounge is re-opened after renovation which is operated from 07:00am till 11:00pm on daily basis; breakfast, afternoon tea & coffee and evening cocktails & canapes would be served from 07:00-10:30am (except Sunday & Public Holidays to be served till 11:00am), 03:00-05:00pm and 05:00-07:00pm respectively. As you are the Diamond Member of Hilton Honors, room upgrade from Main Floor to Executive Floor would be arranged for you accordingly.

Mr X , we appreciate your advice on your arrival time with your flight details at your convenience and look forward to welcoming you soon.

Thanks and Best Regards,
Peggie

I looked at my booking and it had been upgraded to an executive room, so I then cancelled the booking and booked with my 5/10/15 certificate, at AUD$400 for the night I thought it worth it, as no UK/USA trips planned.