The Gray and Wyner lossy source coding for a simple network for sources that generate a tuple of jointly Gaussian random variables (RVs) X 1 : Ω → R p 1 and X 2 : Ω → R p 2 , with respect to square-error distortion at the two decoders is reexamined using (1) Hotelling's geometric approach of Gaussian RVs-the canonical variable form, and (2) van Putten's and van Schuppen's parametrization of joint distributions P X 1 ,X 2 ,W by Gaussian RVs W : Ω → R n which make (X 1 , X 2 ) conditionally independent, and the weak stochastic realization of (X 1 , X 2 ). Item ( 2) is used to parametrize the lossy rate region of the Gray and Wyner source coding problem for joint decoding with mean-square error distortions, by the covariance matrix of RV W . From this then follows Wyner's common information C W (X 1 , X 2 ) (information definition) is achieved by W with identity covariance matrix, while a formula for Wyner's lossy common information (operational definition) is derived, given by