It could well be that OUAT the cables fed a socket or a supply for an electric fire. Since a gas fire was installed, the wires were buried and an extension made to the new "room".
Assuming you are going to fit a new fireplace and fire, it would make sense to reroute the two legs of the ring final to a position where they will not foul the fireplace.
Then a new feed can be taken from this position via an FCU to the new room. If you need more than 13A supply in the new room, you could extend those legs into the room and put whatever is in there on the ring final.
I would fit a socket in the lounge, though. You can never have too many these days.
As to why there is cabling going up the lounge wall, it could be there's a good reason. Is your ground floor solid concrete?
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local