26mph might be a respectable speed for a cyclist but in traffic from a driver's point of view, even on a 30mph road it would be perceived as a slow moving vehicle and will likely build up a queue behind you. Drivers are aware of cyclist vulnerability and ask any of them, they would rather have you behind them than having to worry about you in the front. A bit of consideration for other road users wouldn't hurt. They have slowed down for you and waited patiently behind for quite some time, it doesn't kill you to slow down a couple of mph and allow them to pass, just a bit of common courtesy.