Senior GPC members gathering for a negotiators' meeting inside BMA House had been discussing reports of 'power surges' on the city's tube train network that morning, when in the words of former GPC negotiator Dr Peter Holden 'everything went salmon pink'.
GPs and support staff leapt into each others' arms and scrambled for cover under tables after the explosive device detonated by teenager Hasib Hussain ripped the roof from the bus directly outside their meeting room.
Moments later, they emerged to begin delivering emergency care to victims, leading a response that helped save lives.
Londonwide LMCs chief executive Dr Michelle Drage - a GPC negotiator at the time of the 7/7 bombs, told GPonline: 'We had started hearing the messages about power surges that morning and thought they didn't sound right. Then out of the blue at 9.47am that bang went off.'
The blast was so loud that it 'could only have been an explosion', said Dr Drage.
At a memorial service held to mark the bombings at BMA House last week, it was the silence that affected her most. 'I was standing in the courtyard at the memorial service last week and the thing that strikes me is the silence. When you get silence in London it is unusual. That was the thing after the bomb had gone off - there was complete silence for a while. You couldn’t even hear any birds.'
The immediate medical response after the blast was led by Dr Holden - a GPC negotiator for 15 years until losing out in elections last summer.
In evidence to a Coroner's inquiry into the bombings in January 2011, Dr Holden described the role he played in setting up and managing what was effectively a field hospital, triaging and prioritising care for the many wounded, dead or dying victims.
Speaking to GPonline this week, Dr Holden said: 'My most significant memory is that everyone pulled together.'
Watching then GPC Northern Ireland chairman Dr Brian Dunn calmly hook a patient up to a drip - something he hadn't done for around 20 years - was also a memory that has stayed with Dr Holden.
'We were a team, and a sizeable proportion of the team were the GPC negotiating team of the day,' he said.
Dr Holden had received the urgent care training to take control of a serious medical emergency, but admitted: 'Most people who are trained for this never do anything with it in their lives.'
Within three days of the 7/7 bombings, Dr Holden had written up a full report. Within a week he had prepared a presentation to deliver to groups that needed to learn from the incident.
'What came out of that day was a serious boost of continuity planning for the NHS, which was going to happen because of the Olympics anyway,' Dr Holden told GPonline.
Dr Holden said he was determined not to let the incident affect him, but that walking past the scene of the explosion regularly as he attended BMA House had been tough.
Now, he said, it was important never to forget, but to move on after commemorations this year. 'There comes a point where part of the grieving process is to move on.'
Dr Drage, however, said she had been deeply affected by the events of 7/7. 'I was pretty traumatically stressed, and had pretty bad PTSD about six months later,' she said.
'This was an indiscriminate attack aimed at maiming civilians much like 9/11 – the scale and that randomness we weren’t prepared for. We have all seen people die and be injured, but you never see it on that scale, perhaps apart from the military.'
Dr Drage said London was now better prepared, but those caught up in the bombings would remain marked by them.
'I think none of us feel the same – I certainly don’t. When you have the anniversaries, every time you see the bus it takes you straight back,' she said.
'You do take stock. I did and it does make you live much more for the now. It took many years for me to look at a newspaper or look at anything remotely horrible on TV without welling up.
'People in emergency services and who experience these things who are medical – there is almost an assumption you can deal with it and it doesn’t affect you. But it does. We are not kind to each other as a profession sometimes – putting on a brave face as a profession – we need to be able to ask for help.'