S.S. I haven't resubscribed, but I have a copy of the last print edition, plus my own notes on the immediate heirs.
Just to flesh out what marquess has posted, the present Earl has two sons. but neither one was born from his one and only marriage, so they aren't in remainder. The current hp is his brother, the Hon. Nicholas Charles (b. 1953), but he has only 2 daughters.
The only other one in remainder is a half brother, the Hon. John Philip (b. 1966) , son of the 2nd Earl by his 2nd marriage. He is married, with 1 daughter.
There is also another son of the 2nd Earl, but he was born outside of marriage.
As marquess rightly said, next in line are the collateral branches, but those who are in remainder, descendants of the daughters of the 1st Earl, are in the line of succession only to the Viscountcy. At first glance, each one of them appears to have a significant amount of descendants.
If you need any other information, please let me know.