I'm going in to the office next Thursday. Seriously considering cycle commuting all the way. It's more or less exactly 100km, depending on the route (a bit over if I choose the quieter roads). At this time of year, it will already be light by the time I have to set off, and if I don't fancy riding home at the end of the day, I can take the train.
Only down sides are having to work out how to carry office clothes on the bike, and the fact that we don't have showers in the office, so it will have to be baby wipes. Will also need to arrange access to the secure parking - don't fancy leaving it unattended near Marble Arch all day, even with a hefty lock (and don't fancy carrying the hefty lock either).
Obviously it's much too far to consider doing this regularly, especially with the lack of showers, but as a one-off, on one of the longest days of the year, it might even be fun!