John,

Well spotted.  It is nothing more than a safety guard!  In the mid '60s safety regulations came in that you had to cover the fans on older tractors and also fit mudguard extensions and footboards to these Ferguson tractors.  The latter we long since removed because they are not required if the tractor is for your own pleasure use, but my son wanted to keep the fan guard.  This was a curse because you had to remove it on one side to remove/fit a fan belt or tighten the dynamo for the belt tension.

These guards were made by some company or other - many jumped on the bandwagon to profit from the regulations, similarly the footboards and mudguard extensions.

For our MF 35 , also afflicted with the same inadequacy of the time we made our own having got the pattern from the Ferguson set.

All history now!

John