why would they sell a 2A lamp switch?

[Neale]

The other thing about fuses is that people talk about them protecting equipment, which isn't usually correct. In fact, the chances are that if the fuse blows, it's because something has already gone wrong! Mainly, the fuse is there to prevent a fire if there is excessive current because of a fault. The nominal fuse rating isn't something to rely on too closely either - a normal fuse will probably carry its rated current for at least tens of seconds before blowing, and probably needs at least twice that to blow quickly. That's fine in practice as it gives just a little bit of headroom for switch-on peak currents but will still blow before the wiring bursts into flame!

[routercnc]

For info I just bought a 10A fuse for the plug on an extension cable reel. This was on the high street (Wilko)