I found this to be a major headache when Ron McGuigan and I wrote Wellington's Foot Guards at Waterloo and my current project on the Light Division in 1810. There were two sets of numbers.

1. The first set is administrative. .. the ones you find in the left column of the muster / pay rolls. They are not the numbers used for tactical formations.

2.The second set of numbers is for active service. From Wellington's Foot Guards at Waterloo pages 8 -

"Army Regulations concerning drill was specific about how the companies would be named while on active service. The companies were numbered based on the seniority of the captain. For the Centre Companies, the 1st Company would be the most senior captain’s company, the 2nd Company would be the second captain’s, down through the 8th Company. The Grenadier and Light Companies were excluded from numbering. Furthermore the regulations stated that while in line formation, the Centre Companies would be organized into four divisions, each of two companies. The 1st Company would be paired with the 8th Company and were in the 1st Division, the 2nd Company with the 7th Company in the 2nd Division, the 3rd Company with the 6th Company in the 3rd Division, and the 4th Company with the 5th Company in the 4th Division. Within the division, the lowest numbered company was on the right. The divisions would line up with 1st Division on the right, next to them would be the 4th Division, followed by the 3rd Division, and the 2nd Division on the left. Thus the companies in line would be from right to left: Grenadier Company, 1st, 8th, 4th, 5th, 3rd, 6th, 2nd, 7th, Light Company."

"The theory behind this formation was to pair the most experienced company commander with the least experienced commander, so that he could provide assistance when necessary. Unfortunately theory broke down when faced with reality. The Guards battalions would practice this drill while in garrison or in cantonments, however when on active service their company commanders were often assigned to the army staff. Waterloo was no exception. During the Waterloo Campaign, 40% of the company commanders in the 1st Division were on the army staff or in other billets. The other problem was what happened when a company commander became a casualty? The army’s solution to both these problems was that the place of the company in formation did not changed once seniority was established. When a temporary company commander was appointed, he was likely junior to the other company commanders, the company’s place in the line was still determined by the original company commander’s seniority. This was only changed when the battalion returned from active service or when a campaign ended."

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So theoretically, if you know who the light company and grenadier company commanders were, you should be able to determine which captain led the tactical numbered companies. This might line up the captains with the company numbers with what the memoirs and letters say they were.