According to the GBStamp.co.uk blog A new BPMA Exhibition at Freeling House from August to October will mark the 80th anniversary of British Inland Airmail.
The Post and Go machine will dispense stamps with a new inscription (underprint or overprint depending on who you read), which will also include a pictorial airmail element.
The buried news is that 2nd class stamps will be dispensed instead of Union Flag. Let's hope the IAR machine isn't affected by the sort of software errors that have occurred at Stampex and elsewhere over the last 12 months or so.
Note, I am not planning to make a trip to London to get these overprints. I may have mint examples after Stampex, but no FDCs.
ROC ~ Black Print Rooster ATM Labels - Republic of China (Taiwan) Black print Rooster ATM labels with machine code 111, from Keelung post office.