"Equitector" riding boots up to 19 inch calf or made-to-measure (UK)
"Little Dead Riding Hood" (gothic clothing including gothic/fetish boots up to thigh-high) up to UK size 13 and made to measure to fit the curvy leg! (UK)
"MARISOTA"
Boots for the more curvy leg, available from "Marisota":
Marisota up to UK size 9EEE and a choice of calf fittings (up to about 48cm/19in. calf for 9EEE boots) (UK)
"VIVA LA DIVA"
A range of stylish wide calf fitting boots from "Viva La Diva":
VivaLaDiva.com up to UK size 9EEE (UK)
"J. D. WILLIAMS"
Wide calf fitting boots from "J. D. Williams":
JD Williams up to UK size 9EEE with choice of calf fitting (UK)
ebay listings:
Finding boots that fit a curvy calf has long been a problem. Today, things are much improved, although actual calf measurements on boots tend to vary with shoe size (foot length). But a few makers are offering 2 or 3 calf sizes for each foot length/width. Some are adjustable. Sizes available are typically 17 to 20 inch calf (43 to 50cm). Large calves are often mostly muscle, even on cuddly ladies, so the ankle and foot may be relatively narrow.
If you are tall, then check the height of the boot, and then measure your calf at that level, since the boot might not reach up to the fullest part of your calf. I hope that you find the styles and size you need here.