When typing on an English International keyboard mapped for the UK, there are a few symbols that are difficult to find and type, because the markings on the keys do not match the symbols produced. This is especially frustrating on the command line, where you need # | ~ frequently, and can't tolerate the " and @ being in the wrong positions!
An example keyboard would be the Dell KB216, Part Number 03Y1D8, commonly shipped in the EU.
Here is a quick cheat sheet for the above symbols:
£ = Shift + 3 € = AltGr + 4 ~ = SHIFT + key above carriage return, marked | \ | = AltGr + Shift + key above carriage return, marked | \ # = key above carriage return, marked | \