John,
It is a great job, and I consider myself very fortunate to do it and to have the likes of the Test and Itchen as my "office."
On the chalkstreams we fish single fly only until grayling time when more than one is allowed. Some beats allow nymphs from the off, others only after the mayfly is over, usually 1st July. Fishing is done upstream or up & across.
The old boy was using one of the "company" rods so 8' 6" #5. That is a more or less standard length, but I do prefer a 9' #4 myself and also use a Grey's 9'6" Streamflex #3 in its 10' format for my autumn grayling.
He caught his fish on a shrimp pattern I have been using for many years and has caught an enormous number of trout & grayling since I first tied shrimp Mk 1 in 1971. I'm now on Mk 10 as more modern materials have come along. I don't expect there to be a Mk11, but then I didn't reckon on there being a Mk10 as Mk 9 was very successful. Never say never applies to fly tying as well.
Tippet strength is going to depend on what fly is being used. No point in trying to push a big bushy mayfly pattern 20 yards across the Test on 3lb tippet; you'll need 6lb at least for that, Similarly no point using that 6lb stuff for size 16 klinks later in the year.
It is a mistake to go too light on the chalkstreams. The fish are strong and they have plenty of cover in the form of bankside overhangs, tree roots and of course the classic chalkstream weedbeds to go and bury themselves in, and the b*ggers in any given spot know exactly where every likely bolt hole is. You have to be prepared to bully a fish sometimes. I generally use 4lb as a starting point. I don't like going down much more than that especially for inexperienced rods.
I prefer nymphing myself on the basis that trout & grayling get 80% at least of their food "downstairs" so sticking to the dry fly only rule is to hamper oneself a bit too much for my taste. I will also use a wool indicator attached New Zealand style because most rods simply can't see any but the most obvious fish in the river. So, trying to get them sight fishing just isn't going to work. Despite telling them right from the off what to expect to see the indicator do it would amaze you how many rods just stand there while the indicator disappears.
It's all good fun!