The only British colours carried at Inkerman were those of the 3rd Battalion Grenadier Guards, valiantly defended (our side always 'valiantly" defended) during the retreat from the sandbag battery. The action is described in the Men-At-Arms volume on the Grenadier Guards, among other places. Unfortunately, it doesn't show the colours, but they are also available elsewhere. Another Osprey book, British colours and standards, gives a good overview.
Is your friend making up the 120mm figure by Lost Battalion? If so, he is right to scrap the included flag, it would be 21/2" thick in real life. Also, the flag is of the wrong size and proportions; the original was 6' on the pike and 61/2' flying. The crown is the wrong shape, it should be guelphic; the "VR" reversed monograms are poorly done and noticeably different on the two sides, and the battle honors are an act of the imagination; there are 14 and the Grenadiers only had eight, even when the three from the Crimea were added. On the Royal (not "Queen's until 1881, think) Colour, the honours were Lincelles, Barrosa, Corunna, Peninsula and Waterloo.
Finally, good news. There was a typical heavy fog that day and the colours would have been soaked. They were carried half furled, so that will help your friend and me, for as you may have guessed
D) I have the same kit. I have ordered a nice old War Museum book on the Grenadier's colours from England, and if I get any more inspiration from that, I'll let you know.
Edit: I just sw the heading of this thread. Of the three recent figures of a Grenadier Guard at Inkerman, only the L.B. kit gets the date right. It was 1854!