ICAO airport reference code
 

Where can you find the ICAO airport reference code listings for various airports?

Try this one
http://www.nodomainname.co.uk/files/airports.pdf

or this try this link The Aviation Codes Web Site - IATA / ICAO Airport Designator / Code Database Search

By "ICAO airport reference code", I meant the code that designates what size the airport is in terms of runways/taxiways/etc. For instance the B777 is 4E, but where do you find out which aerodromes can facilitate an aircraft of category 4E.

CAP168 Aerodrome Licensing Chapter 3 Physical Characteristics.

There's a table (3.1)which will help you. 4E is actually a runway length figure and an a/c wingspan / gear width letter.

You're right that a Treb is a Code E a/c as is the 747, A340 and MD-11. The A380 is a code F.

A code 4 runway is longer than 1800m.

I've searched the UK AIP and found it easy to work out the runway code but how anyone works out whether a particular code a/c can be operated into an airport with a variety of different taxiways, I don't know.

SGC