Ranko's answer of the auction of Marlinspike Hall is correct!
As for the year 1958, I gathered it from The Secret of The Unicorn p.189 (as in 3-in-1 Version).
There we see Tintin along with the Thom(p)sons, arrived at Mr. Aristides Silk's house, and arresting him for the crime of pick-pocketing.
From Mr. Silk's collections of "picked" wallets, we can see that he labelled them not only by name, but also the date of the theft. Some examples we see on the page are "Mr R.Biggs pinched on 20-5-58" and the famous Bird Brothers on "1-5-58".
At the end of this book, Tintin and the Captain annouced the beginning of the treasure hunt; as we then move into Red Rackham's Treasure, we find they are at sea in July, geting back to shore on 25 July. Although there is no obvious indication that all these happened within the same year, it is only logical that it did.
This is how I worked out the year 1958. |