[cherryteastain]

The Parliament being sovereign, it can pass an act about anything. It could certainly pass an act forbidding the government from ceding territory to a foreign power. However, since the current government holds a majority in parliament, in practice it won't happen.

[andyjohnson0]

Parliament can pass basically any laws it likes, so it could certainly do that. But that would never happen unless there was a total breakdown of MP party discipline. Hard to see that happening outside of a brexit-type constitutional impasse.

My point was that there is no constitutional requirement for parliament to ratify treaties.