Looks like it is in company service - probably not white, but light gray, the MoW color before changing over to yellow in the '50s. Compare to the white car to the right of it for the (slight) contrast. The 49xxxx number is also a giveaway; that series was reserved for MoW or other company cars. I can't read the stencil next to the car number, but it may indicate the type of service the car had been reassigned to.