15th July does seem to be an odd date to restart being a Wednesday
The majority of restriction being relaxed from the UK government tends to happen on a Monday and restrictions are genuinely reviewed on a 14 or 21 day time frame.
The only other explanation I seem to remember the Greeks saying (i could be mistaken) we may be allowed in from mid July, so are we now using middle of month as the next possible wave of resumption of flights, think we can still say 1st July will see the next increase of flights with Ryanair/Easyjet increasing flights from that date other airlines are all starting on that date into Manchester ie Brussels Airlines/Finnair daily Emirates and even domestic BA LHR 2 daily