In my last post about the Diamond I said I would let you know what the battery life is. I therefore carefully refrained from giving it any charge over the weekend, even when connected to my PC.
That means that it received no power from 5.30pm on Friday until it died (which it did, eventually).
After that time, exchange push carried on notifying me of email immediately on arrival until 8pm, after which it downshifted to checking every hour and continued like that for the rest of the weekend.