The total amount of money raised by the National Lottery for good causes has fallen by £100m in the 20 months since October 2013 when its operator, Camelot, doubled the ticket price.

The National Lottery raised £3bn for good causes in the 20 months since Lotto tickets were doubled in price to £2 in October 2013, £100m less than was raised for good causes in the 20 months before the change, according to its accounts.

The doubling of the ticket price in 2013, was part of Camelot’s overhaul of the Lotto draw after a “decade of decline”, coincided with a two per cent decrease in the amount of the ticket revenue going to good causes.

Camelot confirmed these figures and said the "reason behind the slighlty lower return from the 20-months compared to those that preceeded it, can be attributed to exceptional circumstances in our other games".

Camelot said that changes to the Lotto in October 2013 were in order to reverse what a spokesman called “years of decline”. Camelot have said that these changes delivered an extra £250m over the last two years to good causes.

A spokesman told Civil Society News that Camelot was planning to fresh changes to the game this year in order to increase the amount extra going to charity. From October 10 new numbers will be added to each draw.

Camelot has not committed to diverting a greater percentage of income to good causes. Instead, the spokesman said that: “Our job is to maximise sales,” and said that the better the sales, “the more we give to good causes”.

While the spokesman would not commit to a figure, he suggested that Camelot expects both ticket sales and charitable returns to “increase significantly” with the new changes.

According to its most recent accounts, the National Lottery raised £1.8bn for good causes in the last financial year ending March 31 2015.