This file appears to be complete, but doesn't include the vehicle you quoted. Also, it installs in folder Anglia_One_Mk3 and NOT One_Mk3s.
I suggest the download you really want is this one :
| ||One [Collectors Edition] [4679400 bytes] - OneMk.3_Set_Installer.zip|
File ID: 18149 Date: 03 Jan 2008 - 2725 Downloads
It puts the coaches in the folder your activity is expecting!
EDIT : This pack also installs consists, which include the supplied Class 90 locomotives; you may require the cabview and sounds installed - see the Readme.
Intel i5-4690K (3.5Ghz), Gigabyte GA-Z97P-D3 m/b, 8GB DDR3 RAM, NVIDIA GTX 750ti (2GB) graphics card, Asus Xonar DS sound card. Win 7 Pro 64 bit.