Complex sentence: Peake was the only English-born painter of a group of four whose workshops were closely connected, the others being De Critz, Marcus Gheeraerts the Younger and the miniature painter Isaac Oliver.
Split into simpler sentences: Peake was the only English-born painter of a group of four whose workshops were closely connected. The others were De Critz, Marcus Gheeraerts the Younger, and the miniature painter Isaac Oliver.