A service of commemoration honouring British military and civilian personnel who served in Iraq is being held at St Paul's Cathedral, London.Veterans and relatives of the 179 killed are taking part in the service, with the Queen and Duke of Edinburgh. [LNB]Tony Blair, prime minister when the conflict began in 2003, is among the congregation, joining current PM Gordon Brown and senior defence figures. [LNB]British combat operations in Iraq officially ended on 30 April. [LNB]About 120,000 members of the UK armed forces and civilians served in Iraq. [LNB]Other senior royals, including Princes Charles and William, the Duchess of Cornwall and the Princess Royal are taking part in the service, as are Tory leader David Cameron and Liberal Democrat leader Nick Clegg.[LNB] UK fatalities in Iraq: In images Emotions as UK honours Iraq force A candle is to be lit on behalf of those who lost their lives by Tracey Hazel, mother of Cpl Ben Leaning, 24, from Scunthorpe, Lincolnshire, who was killed when his armoured vehicle was hit by a roadside bomb in April 2007. [LNB]She said she felt "privileged and honoured" to perform the task. [LNB]Speaking before the event, she said: "The service is a fantastic idea. It makes me so proud to be British and a lot of other people should be." [LNB]Archbishop of Canterbury Dr Rowan Williams will bless the centrepiece of the "Basra Wall", built by troops in front of the 20th Armoured Brigade's Iraqi HQ to honour fallen comrades. [LNB]The wall, with its brass plaques and marble centre stone, was the focal point of the memorial service in April to mark the end of the UK operation. [LNB]It is to be rebuilt at the National Memorial Arboretum in Staffordshire, with the help of a contribution from the Iraqi government.[LNB]About 120,000 UK service personnel and civilians served in IraqAt St Paul's, prayers will be read by representatives of each of the armed forces. [LNB]Capt Jon Pentreath, head of the Commando Helicopter Force which supported Royal Marines' amphibious operations over five years, is reading a prayer on behalf of the Royal Navy. [LNB]He said the service would give personnel much-needed recognition. [LNB]"It's important for the nation to understand what members of the armed forces and their families are going through," he said. [LNB]Also involved is Sir John Chilcot, who is chairing the inquiry into the conflict. [LNB]He has invited those who served in Iraq to submit evidence to the inquiry, which is also hearing from bereaved families.