It's a bit strange to be asking this 3 years later...
I agree with the above that some Dr.s always do this after a surgery...some do not...depending on the injury and the surgery.
If you are having pain, then I suggest you seek out a new Orthopedist and get it looked at.
Good luck..
It depends on what kind of work the surgeon did on your knee. Not all doctors have the same opinion on physio. Some insist on it no matter what and others don't think it's all that important. My own experience with orthopedic surgery taught me that it's necessary to return the joint full use or close to it. If you're having problems now, you need to see a doctor. Physio may or may not help at this point depending on what's going on with that knee.
I see you're in the UK and have to deal with NHS. Most doctors here in the US lean on the pro-physio side. It can be a long, drawn-out process depending on the injury which makes it expensive. Cost may be the only reason you were not referred.