It's not an increase- it might be a decrease as the list above has 8 aircraft- there have been 9 in the past.
I have noticed at LTN at least that the reduction from 5 to 4 aircraft has not really amounted to a total loss of one aircraft as more productivity appears to be being achieved from the 4 that are based.
On a Saturday for example the morning ALC (last year) has been dropped from a.m. to p.m. and DLM has been dropped back from p.m. to an evening departure so the only casualty appears to be evening often summer peak only CFU.
Turnround times are also down to 45 minutes at times which was rare in the past - and yet punctuality seems better.