Make an inference about why the solicitors from Whitby (Samuel F. Billington & Son) ask a delivery company in London (Carter, Paterson & Co.) to pick up the fifty boxes of dirt from the train, deliver them to Carfax Abbey, and then leave the keys inside 🏠

From the text, we can infer the solicitors made the request on Dracula's behalf, as they were his representative. We can infer that the delivery company was paid well to carry out the Count's orders.

We might also infer the boxes are filled with something or someone who can unlock the door from the inside.