"Gross negligence" means you really really should have known of the risk. But it's still a contradiction to say that someone was deliberately grossly negligent.
Gross negligence is often more along the lines of "we are 99.999% sure you are lying, but we can't prove it".
In Wilson v Brett Baron Rolfe (later Lord Cranworth) said he "could see no difference between negligence and gross negligence; that it was the same thing, with the addition of a vituperative epithet."