What seems likely to happen is that we're going to carry on meeting in London, so colleague 1 can attend, and continue with phone meetings at all other times.
If colleague 2 declines to travel to London and suggests I go there, I'll be happy to outside term time. During term I'll point out that a face to face with only 2 of us seems pointless. Colleague 1 is unlikely to change their position, I suspect.
As to Skype, video calls or whatever, I've only ever known people Skype from mobile phones or laptops/home computers, both connected to the internet whether wirelessly or cabled. So forgive me for not understanding that it could work indpendent of this, although I don't quite see how.
However, with respect, the issue is that we don't have laptops or other video conferencing facilities.
I can't sit at my desk and use my computer, because as mentioned we work in open plan offices, and are discussing sensitive issues which need to be in meeting rooms away from other staff. There are no computers, nor anything other than basic phones (suitable for a telecon, but not video calling) in the meeting rooms.
So no, I haven't tried to Skype. Given the above, I don't think it would be possible in a meeting room, nor would it be appropriate to do so from my desk. In our organisation, meetings are face to face, if you work in the same office. If in different offices then often they are by phone BUT the expectation is that many will be face to face. Those much higher up the management chain regularly travel not just to London, but to other major cities, not just in England, but Scotland/NI as well, to attend face to face meetings. I'm lucky I don't have to travel that far.