Hats off to the Imperial War Museum which is making parts of its huge photograph collection available online, and allowing free-to-use for non-commercial sites. The chosen pic (above) is a Diamond T tank transporter in British Army service, moving a Churchill Mk I tank through heavy mud at the REME experimental recovery section at Aborfield, Berkshire, 7 April 1943.
To find this and similar, go to the "search" box at the top right of the site. In this case I entered "Diamond T" (without the inverted commas), which gives you this. Spool down the page until you see "Collections". This is a live link, so click it and it will bring you here. You then get presented with a fine list of photographs, any of which you can click and download.
This one here is extremely atmospheric – right-click the pic and its yours.