Originally Posted by Big_Dutch
This is correct. As long as you stay on the "sterile" side of the airport you will not pass through passport control. That said, you should give yourself 45 min - 1 hr to clear security which happens at the gate.
Well, as it stands now, you aren't allowed to leave EDI or anywhere in the UK with much more than a spare pair of knickers, so she shouldn't have much to clear at the gate. What is involved in the gate security? I have done DL flights to JFK and ATL from AMS and IIRC, there was secondary screening at the gate with security questions etc. I can't remember whether hand lugagge was Xrayed again or just examined.