What were the suspicious circumstances about arsenal been promoted in 1919?

Answer 1

Arsenal is the only club that was not ever demoted, so the question of promotion never arises.

Woolwich Arsenal were relegated in 1913 they are the same team only the Woolwich was dropped after they moved to Highbury. In the 1914/15 season they were still playing in the second division as Arsenal. The First Division was increased from 20 to 22 clubs for the 1919/20 season and even though they only finished 5th they were promoted above Barnsley and Wolves and at the expense of Tottenham who were relegated. It is rumoured that their chairman Sir Henry Norris was linked to some dubious backroom deals