Yes, most manufacturers now recommend brake fluid change every two years. It is hydroscopic I.e absorbs moisture from the air. The effect of this is that under prolonged, continuous braking, the heat generated can cause the fluid to boil and lead to brake failure. Also, Morgans in particular seem to commonly suffer failures of rear brake cylinders. (Having water in the system possibly leads to rusty brake pistons.)
Many may argue that as the fluid is contained with only a small breather hole, the incidence of water ingress is minimal. However, for peace of mind, changing it yourself is cheap enough or if you have a dealer to do it, they should have a means of testing the fluid to determine its water content, before committing to changing it.
