If he could access the data in any reasonable manner (ie, encrypted on his laptop, accessed through secure storage, etc.), parliament could require him to give it up. So the only way they wouldn't have been able to get him to give it up is if he didn't have access to the files at all.
He could claim only hard copies exist and he's not carrying any, but then parliament could simply detain him until such time as he produces copies for them, through his lawyer or what not. And of course, he doesn't exactly have any reason to resist an order like this.