Jon
Do you know that is a crcking question. Do you know?

I can only assume the following two reasons.

Negative bowling down the leg side

The other is that a bowler tends to run along the leg side area of the right handed batsmans batting area, and therefore is always going to be rough, which is unfair for right handed batsman.

I will investigate and come up with an answer.

But you will have to come to the Market Rasen Folk Club on Friday to find out the answer. :-)

Les