Exactly, this is my opinion also.Idris wrote:
It has always struck me as odd that this model is simply No. 1, and it confused me when I first came across it as a lad (especially so since it was without the scraper and therefore appeared to me to be a 1-75 series issue).
The presence of a raised platform probably does indicate a renumbering. (If it were there for strengthening purposes, it would be resonable to expect it to be on the other side too). However, the platform area is so small that whatever is hidden underneath it cannot have been very long or wordy. That would seem to rule out Major Pack No. 1, so MP1 or MP-1 probably isn't a bad guess.
Antonin