Red Diesel is not only UK ... but in various countries. The red is only a Dye to indicate it's not for Road use / is different tax etc.
There are various dyes in use in a number of countries including blue, green and red.
A lot of countries use the red colour for Agricultural or Heating designated fuels.
The dye in fact is not the only indicator that shows the designated fuel use ... there are also chemical markers that bond with the fuel - so even if you take out the colour - Fullers earth can do it ... I say Can , it's not guaranteed - the marker will still be there for C&E to find.
Red is also normally higher sulphur content - good for older engines - not so good for modern car stuff.