UK: Imperial Airways airmail labels 2

Here is a booklet of airmail labels from Imperial Airways. Booklets come with 3 vertical strips of 4 labels. Mine is short 5 labels. There are 4 main types of booklet covers.

Year: 2.1931, Gummed. Günter Mair's catalogue no: - GBR-B-1, rouletted H, "BY AIR MAIL": 26.5mm

"PAR AVION": 21.5mm, further dates: 6.1931, 10.1931, 5.1932, 3.1933, 8.1933, 3.1934, blue or

grey-blue/white, 2**