Olasek & Porterhouse, you are confusing a full ICAO compliant IR (which is a requirement if you want to hold an ATPL, like BA pilots do) with the UK-specific IMC rating. The UK IMC rating gives *limited* privileges to fly in IMC conditions, but does not provide you with the full spectrum of IR privileges. For instance, certain minima are higher (like RVR), and you cannot fly in class A airways with an IMC.
If all you know about is the ICAO compliant IR, then it doesn't make a whole lot of sense to comment in a thread that is about the UK specific IMC rating.