Yes, that's the one - I think "Hentschel of Fleet St" were just the printers who pioneered the 3-colour process in the UK. But exactly which of the many 3-colour techniques it was I'm not sure. I suppose it could have been an early form of the modern photographic process with filters. When I said above "From memory only her first one or two books were printed using wood blocks.." I might have been thinking of Kate Greenaway. A quick look at Bamber Gascoine does not clear up any of this.