I guess it is something like this:
Gatwick 43
Malpensa 18
Luton 16 (maybe only 13)
Stansted 13
Bristol 11
Paris-CDG 9 (10 from 14th May)
Liverpool 9 (10 from June)
Geneva 9 (10 from June)
Berlin 9
Madrid 8
Paris-ORY 7
Belfast 6
Newcastle 6
Manchester 4 (5 from May)
Basel 4 (5 from 25th June)
Rome 4
Glasgow 4
Edinburgh 4
Lyon 3
Doncaster 1 (from 19th April)
LGW, MXP, CDG, LPL, GVA and MAN gained the most (2 or more a/c)
ORY, BSL, FCO (wasn't a base last summer - flights were op. by MXP based a/c), LYS and DSC (new base) gained 1 a/c.
EMA isn't a base anymore and lost 3 a/c