@DreadPirateRobots
"This is why you don't contest a will. Nobody wins but the lawyers. It takes a special kind of arrogance to take it this far, though."
I agree about the lawyers. The lawyers are always the main winners.
However, I was once advised that if a significant person was missed out altogether, then the will can be contested (ie the person may have just forgotten them). In this case, the granddaughters were each left 50.00, and a reason given for why it was not more, so the Judge decided the reasons were justified, etc.
In the UK, there is no law that states children have to be left anything at all.
The testator can leave it all to someone else entirely, but they should state their reasons for doing so.
Unless the sisters had any evidence that undue pressure was exerted on the grand father, then their case stood no chance at all.