All the No4T rifles were slowly modified with the front trigger guard swivel as a result of snipers being taught to use the single point sling method as an alternative to the well established top and bottom sling loop method. In wartime, a rifle could go for years without going to an Armourers shop or even being noticed, especially if the sniper didn't know or didn't use the front trigger guard sling swivel. So both with or without are correct. The same goes for cheek rests on the earliest No4T's. With or without are both correct.
I suppose that if you had an original rifle, straight from the battlefield in Italy, fitted with a long Bren webbing sling (which was well liked, taught and used more often than not....) then THAT would be original too.
But, be warned, there are two sorts of front trigger guard swivel. The VAOS part (that's the Army spec one) has a short shank that will not allow the swivel to rotate a full circle as it get stopped by the cover loop on the trigger guard. The commercial sling loops have a longer shank that clears the loop.
As for the cover loop on the trigger guard, then while I insisted that they were present, other armourers, some senior and some junior, said that it was academic and didn't mind either way............... The reason for NOT replacing them was that a change of trigger guard meant that you had to spend the next couple of hours re-setting up the trigger pull-offs! Some say that about 50 percent of the L42's disposed of didn't have the loop......