Hi Paul,
I agree with outofsynch, but would go a stage further and say he probably WAS using the LAM VOR, rather than being hand-vectored... here's why:
It certainly sounds likeliest that he was out of Gatwick, on a LAM4M/4V or LAM5P/5W SID (Standard Instrument Departure) which would've put him at LAM VOR at 6000ft, heading 340 degrees (which is pretty north-ish, when viewed obliquely from the ground!)
From there, he's probably Edinburgh, Glasgow or Inverness bound, would be my guess. Those appear to be the only Gatwick-departing choices for airports north, according the EZY website.
What time of day did you see him? It might be possible to work it out from that?
It also might be worth checking for the winds on that day/time... if they were easterly, Gatwick would've been operating out of 08L and 08R, which would account for the traffic leaving for the north via LAM SIDs, rather than the more usual KENET SIDs west then north off of 26L & 26R. Easterly ops are 'unusual' insofar as the prevailing wind is most often a westerly, but it's not uncommon, by any means.
I would've expected him to make a 8 degree turn left, though, at LAM (which again may have been imperceptible from the ground, perhaps?), to get himself on the N601/UN601, heading 332 degrees, probably all the way to POL VOR (Pole Hill), which is pretty standard for (at the very least) the Glasgow LANAK1A STAR via MARGO and TLA, and probably all the Scottish airports for all I know (I can check if you're interested).
Hope this helps! Thanks for giving me an interesting lunch-hour playing EZY detective!
Been fun!