Offhand, I can deduce very little. Only that the words are written with a broad-pointed quill pen which has spattered, twice.
11 seconds sound clip from the The Great Mouse Detective movie soundboard.
You can hear this line at 00:38:24 in the Blu-ray version of the movie.
Quote context
[...]
- Fidget, you delightful little maniac.
- You've presented me with a singular opportunity.
- Poor Basil! Oh, he is in for a little surprise.
- That the paper is of native Mongolian manufacture, no watermark.
- And has been gummed, if I'm not in error by a bat who has been drinking Rodent's Delight...
- A cheap brandy sold only in the seediest pubs.
- We still don't know where it came from. Perhaps a closer inspection will tell us something.
[...]