Taking a child out of school for holiday

Took my son out of school for a holiday on the last week of term. I did ask permission as I work shifts and it was a late booking but got refused. I checked there was no exams or tests and as it was the last week before the summer holidays the pupils would only probably be doing little work and a holiday to a foreign country would be more educational than playing games and watching Dvd's. I did expect a fine of £60 but have now been told it is £60 per parent adding up to £120. Is this right? It's not the paying of the fine it's the principle of it. Checked the government website which does not mention the fine is per parent just per child