Not sure about parental responsibility. I alway thought that unless there was a court order to the contrary it is assumed that both parents have joint responsibility whether the child lives with tthe parent or not. This means that you have a right to input on how the child is brought up, what school they attend, etc and whether the child should be allowed to leave the country. If your ex is taking you to court then the court will decide whether you are being ureasonable. Does she intend coming back? What reason do you have to suspect she might not?. Contravening your right to access and the childs right to access to you in a foreign country might reinforce your argument . After all the cooperation and responsibility you have shown the court might think this is a step too far. I strongly advise you to seek professional advice. Social Services and CAB might be a point of contact..