[holding answer 15 January 2008]: The units serving in Iraq can be found on the MOD website at:
http://www.mod.uk/DefenceInternet/FactSheets/Operations Factsheets/OperationsInIraqDetailsOfBritishAndCoalitionForces.htm
and are listed as follows:
4th Mechanised Brigade Headquarters and 204 Signal Squadron
The Royal Dragoon Guards
1st Battalion Scots Guards
The Royal Scots Borders, 1st Battalion The Royal Regiment of Scotland
1st Battalion The Duke of Lancaster's Regiment (King's, Lancashire and Border)
1st Battalion The 22nd (Cheshire) Regiment (1st Battalion The Mercian Regiment as of 1 September 2007)
21 Engineer Regiment
12 Logistic Support Regiment, The Royal Logistic Corps
1 Close Support Medical Regiment
Elements of 845 Naval Air Squadron (Sea King)
Elements of 847 Naval Air Squadron (Lynx)
D Battery, 3rd Regiment Royal Horse Artillery
K Battery, 5th Regiment Royal Artillery
Elements of 33 Engineer Regiment (Explosive Ordnance Disposal)
62 Works Group Royal Engineers, 523 Specialist Team Royal Engineers (Works)
Elements of 3rd (UK) Division Signal Regiment, The Royal Corps of Signals
Elements of 1st (UK) Armoured Division Signal Regiment, The Royal Corps of Signals
Elements of 10th Signal Regiment, The Royal Corps of Signals
Elements of 14th Signal Regiment (Electronic Warfare), The Royal Corps of Signals
Elements of 21st Signal Regiment (Air Support), The Royal Corps of Signals
Elements of 6 Supply Regiment, The Royal Logistic Corps
Elements of 16 Tank Transporter Squadron, 7 Transport Regiment, The Royal Logistic Corps
Elements of 11 Explosive Ordnance Disposal Regiment, The Royal Logistic Corps
Elements of 84 Medical Supply Squadron, 9 Supply Regiment, The Royal Logistic Corps
Elements of 150 Transport Regiment (Volunteers), The Royal Logistic Corps
Elements of 24 Postal, Courier and Movement Regiment, The Royal Logistic Corps
Elements of 29 Postal, Courier and Movement Regiment, The Royal Logistic Corps
Elements of 148 Expeditionary Forces Institute Squadron (Volunteers), The Royal Logistic Corps
Elements of 1 Battalion Royal Electrical and Mechanical Engineers
115 Provost Company, 1st Provost Regiment, Royal Military Police
Elements of 102 Military Working Dog Support Unit, Royal Army Veterinary Corps
Elements of 1 Military Intelligence Brigade
No 28 (AC) Squadron, Royal Air Force (Merlin)
619 Tactical Air Control Party, Royal Air Force
627 Tactical Air Control Party, Royal Air Force.
The information requested is not held centrally and could be provided only at disproportionate cost.