I'm back and am going to be doing a considerable number of nights here on business over the next few months. This evening the clerk just nodded at me when I came up to the reception but when my status popped up he straightened up quickly and couldn't have been politer

He remembered everything without having to be prompted. I don't imagine they get a lot of diamond guests.
I am now sitting in a decently-sized deluxe room with separate desk and work area. Two bottles of water, one quarter-bottle of wine and a bar of Cadbury's Dairy Milk.
Internet code I got didn't work, but I just phoned reception and got the same clerk, and a new code.
Can't really recommend the restaurant/bar, which charge standard Hilton prices (or even slightly more) despite the location well into the country. My dinner expenses limit would be hit with just a main course and a drink. Hearty recommendation on the other hand for the Toby Carvery a mile up the road (towards central Northampton) where two gigantic courses and a drink came in at £13.86. (After 7pm meals include unlimited curries Mon-Thu.)