Have you tried contacting Hayter?

There are some Hayter colours available online, but completely unaware of any paint codes. It’s usually listed as ‘Hayter Green’ although there is a ‘new’ version of the colour to confuse matters.

I don’t know the colour for the Murray mower but there is a link between Murray and Mountfield mowers through manufacture, so on some older machines they have the same colour – may be worth investigating although there is more than one shade of Mountfield red!