Jamie,

Please note that recently (including yesterday when I was a victim of it) Fast Track security (air to air) or immigration (air to land) have been closed due to redeployment of staff to check departing pax. This meant that all lines were horribly long at 7AM, except the UK/EU/EFTA (Swiss) immigration lines, so I made use of my dual nationality to skip the lines, go landside and then back airside. Land to air fastrack at T4 was open, but as I was transferring with bp already printed, they did not allow me through there without the proper 'invitation' . Never the less, I saved time by visiting the UK for 2 minutes on my T4-T4 transit.

In order to give you proper advice, it might indeed help if we knew the direction of travel, flights, dates (or at least which day of the week) and incase of fastrack closure, your wife's nationality.