Possibly not E/W as you suggest, on further consideration it's more likely along the Great Glen or even North/South.
It's doesn't appear to be SAR related, these are pretty frequent over here & are almost without exception Sea Kings or Bristow Coastguard S-92's. Lossie, Gannet & Stornoway helicopters all approach from their own familiar directions, but these Bristow helicopters appear to be on an almost regular route?
Thanks.