As the 2140 does not contain a DVD drive it’s necessary to do the install off a USB key. The interblag contains a number of articles describing how to accomplish this (for instance here) however to install I found a small modification to be necessary. The USB key I was using is 4Gb which the BIOS turns out to be unable to read. During the partition of the USB key specifying SIZE=3072 enables the BIOS to read it and is sufficient to contain the Windows 7 install files.