FFHKG,
Interested to know how true your statement about T3 security is? The reason I say this is because of the following:
T3 only has 11 physical security lanes. Therefore, your statement of 13 lanes is inaccurate.
Out of those 11 lanes, Lane 1 is obsolete due to it being right up against the wall, and has not been used for many years.
Lanes 2/7/8 are back up contingency lanes only due to having older equipment and less space, so, only used during exceptionally busy times
Lane 3 is for oversized items only, such as pushchairs and sticks.
This means, MAN only has 6 lanes (4/5/6/9/10/11) to open on a normal basis. Now, the way MAN operates is that security is open 0400-2145, but opens 0330 for staff but allows pax anyway. 0330-0400, usually only lane 4 is open. At any one time, the standard config is to have lanes 4/5/6/11 open, with 9/10 when it gets busier and then 7/8 if it gets really busy.
Therefore, unless the machines were down for maintence for any reason, I severely doubt only 2 lanes were open at 14:15 on a Tuesday. That said, 30 minutes if the queue was all the way back through the enterence, knowing that area well, I would say 30 minutes is actually quite fast and throws even more doubt into 'only 2 lanes open', as the area you describe can hold about 550 people, so, if it was a big queue in that area as you describe, 550 people in 30 mins is actually quite good and no way only 2 machines could process that amount in 30 mins. Also with what has happened in Manchester in the last few weeks, do you not think security would be heightened at this moment in time?
30 mins is also better than a lot of airports I've experienced lately, LAX was well over 50 mins, DFW similar, LHR had a wait of 45 the other day (not the BA meltdown days before anyone asks). BHX was in the press for its long queues too the other day. So, it's not an isolated issue.