Thanks everyone! Some of the above we'll have to try on our next trip as the weekend did not turn out exactly as planned...
In short, the river locks were closed on Saturday so we stayed put at Upton - a hangover-inducing night in the new Wheelhouse pub at the marina. (Great Sunday lunches by the way, but that was last week...)
We got up early on Sunday and called the Diglis lockeeper. He said we could go through under indemnity terms so we set off upstream, locking through without any issue...until we came to the Diglis basin top lock, which was chained up! Clearly some sort of communication issue with the Diglis lockkeeper as I am certain he said the locks up to the basin were open. Luckily, we met up with another boater who had made arrangements with a CaRT chap to let him through at 2pm. We took both boats up into the top lock, and stopped for lunch while we waited to be let through. The rest of the trip was pretty uneventful although it was well into dusk by the time we made it to the 3 locks of the Hanbury flight. We didn't speed although I got a funny look from the occupants of a moored boat as I motored past on tickover with a plate of roast chicken and vegetables in my hand, tiller tucked under my arm! As there were four of us aboard, we were pretty efficient through the locks all day but we excelled ourselves through the last 3 and gladly pulled into Droitwich Spa at the end of a long and tiring day.
We'll save the barge canal for another time. Cheers!