If you suspect that an LTR application is going to be made by the other parent you are advised not to sit on your hands waiting but to make your own application for a Prohibited Steps Order (PSO).
There is always a chance that a parent won’t follow appropriate procedure or comply with the court’s decision and will simply take the children abroad anyway. For that reason your application will need to be an emergency ex parte one. Also ask the court for the children’s passports to be surrendered to an independent solicitor for safe-keeping until the matter is resolved.
PSOs are difficult to obtain, however, and there are certain problems associated with them; please read our section on PSOs which explains their limitations. A PSO is only ever temporary and cannot be made if another order is better suited to the circumstances.
The court will normally be reluctant to agree to the PSO ‘because for the court so to do would be an unsustainable restriction on adult liberties and would be likely to have an adverse effect on the welfare of the child by denying the primary carer reasonable freedom of choice’.
If you don’t already have one, you can apply for a shared residence order at the same time. Think carefully, however: will it look vindictive? Is there a reasonable chance of success? Is residence realistic and practical for you? You will need to present a very detailed and convincing parenting plan for it to work.
At one time the courts would refuse a Shared Residence Order (SRO) if there was a considerable distance between the parents, but the case to cite is Re F (Shared Residence Order)  2 FLR 397. An SRO is not regarded as a bar to removal, though it will help.
A solicitor will normally advise against this course of action and tell you it is aggressive and likely to inflame the situation, but it is far less aggressive than the alternative. If you do nothing and wait to be served papers which may never come, your children could be out of the country and beyond the reach of the courts before you know it.
 Nigel Lowe, Mark Everall & Michael Nicholls, International Movement of Children (Practice & Procedure), Jordan Publishing, August 2003