I have recently sold my iPhone and it has been stolen in postage, it is wiped what are the best steps to take in locating the phone?

File a complaint with the post office. The only way to remote track it would be to have your iCloud account signed in on it with find my iPhone enabled. And it would have to be powered on to ise the find my iPhone feature. I assume since you say you wiped it you also disabled find my iPhone. All you can do is get the post office to investigate and perhaps locate it.

File a claim with who ever the shipper is.They can track it. If not they should reimburse you for the value of the iPhone.