Chris,
While I agree there are no conclusive evidence the photos still do tell a tale. There IS a difference between the letters, and the colour cannot be the same as the sky band and the individual letter.
I just scanned this picture. Note the colour demarcation between the sky band and the white undersides. The temporary paint was apparently removed with gasoline or similar and thus the sky band has been exposed.
The question that really isn't answered is WHY would they need to repaint the TP letters if the invasion stripes was washed away and not overpainted?
One plausible answer could be that the Typhoons were received with no squadron letters to start with, simply because the invasion stripes were painted on at the factory before delivery, alternatively at the propeller/tailplane-changing facility. When the top stripes were ordered removed come July they had to apply squadron lettering for the first time, while the individual letter would be painted in front of the stripes at an earlier stage.
It does make sense that they simply haven't got the right paint at a certain point in time.
Whether this paint actually was red remains to be said, but the tonal values/hues certainly seem to be in the same range, also if you use photoshop to transpose paint from the lettering to the roundel centre. A slight difference could be explained with the letter-red not being roundel-red...
Two pics, the first as scanned, the second with a slight change for greater contrast.
Very interesting discussion I might add,
Kyrre