Autobox stuck in safe mode?

From standstill, my car seems to be pulling away in 3rd gear and then selecting 4th gear once up to speed. I’m currently selecting “2” on the gearstick to throw the gearbox into the lower gears before selecting “D”.

My knowledge of auto gearboxes is pretty limited but I was wondering if the box could have entered into a safe mode and jammed itself into 3 and 4th gear to protect itself.
Or maybe it’s just knackered.

Thanks

btw I drive a 1995 Rover 827Si (British cosmetics - Japanese guts)