Martin I beg to differ about Herald owners/drivers oiling nipples.
According to a 12,000 miles service on a Herald, Rear hubs apply grease gun and give five strokes only.
Water pump apply a grease gun to the nipple and manipulate the gun until grease exudes from the overflow hole on top of the pump.
Steering unit apply a grease gun to the nipple and give five strokes only. Over greasing may cause damage to the rubber bellows when the steering is turned to full lock.
It's your steering lower swivel you oil at around 6,000 miles. I can't find anything about front hubs but I think I know what's wrong with the slack fan belt now.