Correction, they were described as "Dwarf Spiraea, lime leaf."

I've used Google Images, and a couple of books, and am thinking they're S.x Bumalda, maybe 'Anthony Waterer."

Looks like it. I'd call it Spiraea japonica, however, 'Bumalda' being another cultivar of that species, as in S. japonica 'Anthony Waterer', S. japonica 'Bumalda' and so on.

You must be a Hillier fan, then. He calls it S.j. 'AW.' Dirr, on the other hand, calls it S. x bumalda (Bumald Spirea) and say's it's one of the hybrids of S. albiflora and S. japonica.

Uconn Hort agrees with Dirr, and goes a step further, saying AW is frequently confused with S. japonica.

Which brings us back to "I'd call it S. japonica."