I would like to create a map of the area of my fictitious Cornish branch line.
Can anyone recommend any free map drawing software that allows a completely fictitious map to be created ?

Try Googlemaps.

They have my place of employment as around half a mile away from where it is situated, not much fun for potential visitors who 'google' us in advance though...

   

If you Google 'Map Making Software' you will find plenty to choose from.

trevor can you mark where you hidden the buried treasure . Cheers john

Click here

Another Trevor