The painting of Nelson's death had quite a few errors.
The orlop deck where the surgeons area lay and to where Nelson was taken was the lowest beck of the ship and below the waterline. The height between deck and deckhead is only about 5 foot. The painting shows them standing which is an error. It also shows a well lit area. There was no natural lighting and only a few lanterns could be hung. The reason for this was it lay on a route to the powder rooms and the risk of igniting powder split by the powder monkeys was high.
The tradition of drinking the sovereigns health sitting down in the RN stems again from the low height 'tween decks. On a ship of the line, such as the Vistory, the main cabin can just about be stood in by someone of about 5'5". on smaller ships such as frigates the deckhead was even lower.