1948 Polish "service suspended" mail to Palestine: 8-4-1948 uprated airmail postal stationary (VI-1937 edition) from WARSAW to TEL AVIV, franked 25Zl in place of obliterated pre-war pre-printed frank & tied by local machine cancel; as under-franked for airmail, marked by bilingual Polish/French "Insufficient fee for air transport" & sent by surface mail, here via UK: but as of 7 APR, UK suspended surface mail to Palestine, so marked by British "No Service | Return to Sender" instructional marking handstamp K-Type-IV. The cover would have been marked by the "Air Mail Service Only" instructional marking, but the cover reached the UK after the 25 April airmail suspension; returned to sender. Opened gently at back (possibly mailed unsealed).