I have created this topic as the post is often quite slow and some people need a SIM card for their phone ASAP. Some members of this forum are willing to hand deliver SIMs/micro-SIMs/nano-SIMs to people living near them - if you are willing to hand deliver, please PM me with the postcode(s) you are willing to deliver to, your email address (this will not be displayed publicly) and whether you also have a nano-SIM cutter and can give out nano-SIMs.
I too can deliver in London. However I think it is fair to say that I (and I doubt anyone else) would go too far in London just for one sim as it would cost too much in transport alone and take a lot of time. Please put me down as any London with very good availability in central London and South East (SE22). In those areas, I can usually be there with very short notice.