Put Another Nickel In!
A Meccano boy grows up.
In 1925, which is the date of the guarantee slip, an anonymous Swedish Meccano boy got his first outfit - an all-nickel number 0. According to the instruction book (that by some kind of miracle has survived), these are the parts to go into that set that year.

The interior of the box hadn't survived, though, but here it is restored. (Sorry for that awful turquoise colour of the photo which doesn't pay justice to the original!) The box layout is copied from Meccano's "Magic Carpet" catalogue, British edition, of 1925.
Probably in 1926, he added this accessory outfit - making his set a Number One. If you compare the contents of the boxes illustrated above with the Number One of 1927, you'll miss the Curved Strips (part no. 90a) and the Braced Girders (part no. 100) which were added to the No. 0 and 1 in 1926. It wouldn't have embarrassed our Meccano boy, though, for they aren't used in any of the models buildable with Outfits 0 and 1 in his new 0-3 instruction book, printed in 1926.
As the accessory sets were scarcely (if ever) illustrated in the catalogues, and the parts card is gone, I have no idea of the original layout.
In 1927, things are getting complicated. The interiors of the boxes were now orange instead of green to make a stylish background to the "New Meccano" colour scheme in Nickel, Pea Green and Apple Red. All-nickel outfits were still available, though, and their contents were updated. There are two long Braced Girders (part no. 99) included in this set, since there should be two 99's (as well as two 100's, of course) in a Number Two of 1927. But the 99's aren't used in any of the models buildable with Outfit Number Two. The 100's are, though - but our Meccano boy can't find them anywhere!
Again the parts cards are missing. Note also that there is no compartment big enough to house the newly-introduced Braced Girders.
Finally in 1928, he got this accessory outfit No 2A, making his set a (sort of) Number Three. The 1928 set includes a striking new part, viz. the Boiler. What to do with a Boiler? He doesn't know, unless he has the new instruction book. But he certainly will miss that three-inch pulley which was removed in 1928! In fact, in due time he will miss all four pulleys which were added to Outfit No 1 in 1928!
But there was help to get. Apart from the "A" series of accessory outfits, there was also a curious line of "B" outfits issued in 1928, e.g. a "3B" to update a Number Three of 1927 vintage to a Number Three of 1928 - provided that you had a complete Number Three of 1927, of course.

Now if our Meccano boy had gotten a complete No 3 in 1919-25, it would have looked something like this! Quite different, isn't it?