Here's a new Clutch Master Cylinder (5/8") & Slave Cylinder Assembly for the following models with a Diaphram Type Clutch from Triumph-

TRIUMPH

Triumph Herald    (1965-67 with Diaphram type Clutch)

Triumph Herald   (1967-71 All models).

Don't muck about - just replace them both.

(Some Heralds of 1965- 67 also used Diaphram Type Clutch).

This is the later Slave Cylinder for the Diaphram Type Clutch which has the groove all the way round.

The earlier Slave Cylinder for the Coil Type Clutch has the groove only on one side.