I used to work for a very large UK company and got involved in a case like this. I had to deliver a guys laptop to our security group for investigation and I remember them telling me that they accepted porn sites could be designed to inadvertently draw you in but the key was how long did it take you to close it down…..and did you revisit it.
The BBC states he was viewing in the Chamber AND in a Select Committee so that doesn’t sound like a one off error to me.