Lieutenants
Lieutenants are the support unit for the British infantry early in the game. The lieutenant is armed with a Mk. 2 Sten SMG and is weak on his own. The lieutenant provides offensive bonuses and speed bonuses to the infantry. Lieutenants are created from the command truck in the beginning and is vital for further evolution of the British command structure. when it gets veterancy, you can have it commit heroic charges with the men reducing pinning and suppression effects. He can also call off map artillery rounds at a cost of munitions. Lieutenants empart bonuses on nearby troops and structures, therefore they should be kept with the main infantry group or used to defend the main base while the main squads are out.
Weakness
The lieutenant usually stays behind the over-watched infantry, potentially removing his firepower from a firefight if lacking line of sight. If the over-watched infantry section retreats, the lieutenant will regularly walk back, not run back with the men, so you will have to manually retreat him, but this is usually unnecessary as they can withstand enough fire to make an unassisted retreat.