I was late with my mortgage payment twice early this year. It didn't go out on the 1st of the month, but when the bank reapplied for the payment on the 15th of the month it was paid. This happened 2 months in a row. (hard to catch up with 2 payments coming out of one months pay, so took 2 months to get back on track).
I applied for my ICB report recently and I have no missed payments recorded.
The trouble this might cause me tho is if I tried to remortgage with the same bank they will have access to this info. And if I tried to remortgage with another bank and they asked for my mortgage statements for last 6 months or more and it was within the time frame they wanted, then I doubt they would entertain my application!