as per YT:

1954 Fordson Major at Banbury Steam Fair http://www.banburysteam.com at Bloxham in Oxfordshire UK on Sunday 28thJune 2010 ,the first tractor in the demonstration ring on Sunday afternoon. Not many people at the show saw it because they were watching England in South Africa get knocked out of the 2010 football world cup by Germany on the TV in the beer tent .
Its not strictly speaking square wheeled but the shape varies between maybe between a 6 sided hexagon , rectangle , rhombus , parallelogram, trapezoid , so its much simpler to say square wheels .
The rear wheels were called Rotopad. Converted by Rotary Hoes Ltd., later called Howard Rotopad tracks. They are a type of track unit to achieve a Low Ground Pressure for working on soft surfaces. They were designed to replace the wheels on a tractor .The machine was used for cutting trenches in which originally were laid clay pipes for land drainage. These machines were developed over the years, certainly until the late 60s at which time they would be laying continuous plastic pipe, which of course is still used in land drainage today.
This machine is a drainage trencher used for digging a trench the trencher which then laid the pipes as it moved slowly along putting clay pipes into wet land. After the pipes had been laid a tractor with a trailer having a side blade came along pushing the soil back into the trench. The machine is a Standard Fordson tractor with tracks that walked the machine along subsequently giving it better traction with less pressure on the ground than a wheeled type . They may look cumbersome but they were excellent when the going was wet .
A slow motion clip at the end of this video,see if you can work out how the Rotopads work .