An ancient gate

This is the gate into Brougham Hall (pronounced Broom) which is a fortified house dating back to Elizabethan times. The gate is partly original but it has been renovated. The doorway which is open is very low. Anyone over about 5 foot 4 inches would have to stoop to get in. Was it designed like that so that anyone who entered had to stoop so that the defenders could give them a good sticking if appropriate? Damned clever our ancestors in the wild north.