The voting was conducted on Twitter with Athelstan defeating Elizabeth I in the final by 50.5 per cent to 49.5 per cent.
To get to the final, Athelstan beat Queen Victoria, King Edward III and William the Conqueror.
Mr Holland said: ‘I thought it was going to be a walkover for Elizabeth. I’m really surprised. It’s like Emma Raducanu going all the way at the US Open. Unexpected.
‘Athelstan was one of the founding fathers of England. I think people tend to assume that England has always existed.
‘He was a great conqueror, but he was much more than that.’
Athelstan, who reigned from 925 to 939 AD, united the country in the year 927 after merging the kingdoms of Mercia and Wessex and driving the Vikings out of Northumbria in the first two years of his reign.
In 937, at the Battle of Brunanburh, Athelstan defeated the combined invasion forces of the kings of Scotland and Dublin.
Sovereign Athelstan beat all other kings and queens of England – including front-runner ‘Good Queen Bess’, Elizabeth I – to be crowned England’s greatest monarch in the podcast poll