Here's a list of Android 2.3.5 Gingerbread firmware update for a carrier branded version of Samsung Galaxy S2 by Orange. This firmwares are official build by Samsung and releases via OTA (over the air) or Kies server. The firmware build date is October 24, 2011 with build number of I9100BVKJ4. Although it has the same build number but each regions provided with Orange network has different CSC file version which is an specific country code for a local language or either with a default regional applications. Just see the list below for it shows a detail on each particular region.
Austria (Orange) GT-I9100LKAONE
France (Orange) GT-I9100LKAFTM
Poland (Orange) GT-I9100LKAIDE
Romania (Orange) GT-I9100LKAORO
Spain (Orange) GT-I9100LKAAMN
UK (Orange) GT-I9100LKAORA
The I9100BVKJ4 stock ROMs are avialable at XDA or at sammobile if you prepare to flash it using Odin.