The cover illustrated here, sent registered airmail from Leningrad to England originally franked with three stamps including the remaining 1r "Telegraph Office", has an interesting cachet on the reverse reading in French "Received at Leningrad, in damaged condition, the flaps of the envelope messily sealed". This is one of a number of cachets found on outgoing international mail from the Soviet Union in the 1920s and 1930s indicating that the mail had been received by the Postal Authorities in damaged condition and were applied at Moscow, Leningrad and Kiev.
It is believed that these markings indicated censorship of foreign bound mail. As the censors tried to open the mail clandestinely, they frequently damaged the envelopes and these markings apparently served to explain away traces of clumsy handling.
Many of these "damaged condition" covers seem in good condition or with some wrinkling to the flaps which suggests that the flaps were steamed open. This probably explains the Authorities need to specifically mention flap damage "Received at Moscow with the flaps poorly sealed" or as in this case "Received in Leningrad, in damaged condition, the flaps of the envelope messily sealed".
Similarly the Air mail and Registration labels have been lifted and replaced and the missing stamps were either removed in the search for secret messages or to add to the distressed appearance of the letter upon arrival at its destination.