This set is identical to GS48, merely renumbered for export as far as I can tell.
The correct contents of the set would be a 1138 transporter with a red cab and blue trailer with six cars. The cars would be 491 (red or blue), 251 (brown) or 340, 252 (maroon), 226 (blue or maroon with cast wheels), 249 and 333 or 321 (signature version). It is, of course, difficult to assess how original content is now but the sets did tend to have the less common colours for the Imp and Rover and blue versions are probably replacements by people who lost the others.
I now have a superb 249 Mini which I’ll include in place of the 321 Mini Cooper. The links will show you more detail of the individual components
This set comprises:
The worn box for 1138 is included in this price.