UK butterflies belong to 7 Family Groups:
Papilionidae - Swallowtails
Nyphalidae - Fritillaries & others
Pieridae - Whites
Satyridae - Browns
Lycaenidae - Blues, Coppers & Hairstreaks
Riodinidae - Metalmarks
Hesperiidae - Skippers
Be wary of colourful names: the Marbled White belongs to the Satyridae (Browns), the Brown Argus belongs to the Lycaenidae (Blues) and Clouded Yellow & Orange Tip are Pieridae (Whites)!
Swallowtail - Papilio machaon
Comma - Polygonia c-album
Dark Green Fritillary - Argynnis aglaja
Glanville Fritillary - Melitaea cinxia
Heath Fritillary - Melitaea athalia
High Brown Fritillary - Argynnis adippe
Marsh Fritillary - Euphydryas aurinia
Painted Lady - Vanessa cardui
Peacock - Inachis io
Pearl-bordered Fritillary - Boloria euphrosyne
Purple Emperor - Apatura iris
Red Admiral - Vanessa atalanta
Silver-washed Fritillary - Argynnis paphia
Small Pearl-bordered Fritillary - Boloria selene
Small Tortoiseshell - Aglais urticae
White Admiral - Limenitis camilla
Brimstone - Gonepteryx rhamni
Clouded Yellow - Colias croceus
Green-veined White - Pieris napi
Large White - Pieris brassicae
Orange Tip - Anthocharis cardamines
Small White - Pieris rapae
Wood White - Leptidea sinapis
Gatekeeper - Pyronia tithonus
Grayling - Hipparchia semele
Large Heath - Coenonympha tullia
Marbled White - Melanargia galathea
Meadow Brown - Maniola jurtina
Mountain Ringlet - Erebia epiphron
Ringlet - Aphantopus hyperantus
Scotch Argus - Erebia aethiops
Small Heath - Coenonympha pamphilus
Speckled Wood - Pararge aegeria
Wall - Lasiommata megera
Adonis Blue - Polyommatus bellargus
Black Hairstreak - Satyrium pruni
Brown Argus - Aricia agestis
Brown Hairstreak - Thecla betulae
Chalkhill Blue - Polyommatus coridon
Common Blue - Polyommatus icarus
Green Hairstreak - Callophrys rubi
Holly Blue -Celastrina argiolus
Large Blue - Maculinea arion
Northern Brown Argus - Aricia artaxerxes
Purple Hairstreak - Neozephyrus quercus
Silver-studded Blue - Plebeius argus
Small Blue - Cupido minimus
Small Copper - Lycaena phlaeas
White-letter Hairstreak - Satyrium w-album
Duke of Burgundy - Hamearis lucina
Chequered Skipper - Carterocephalus palaemon
Dingy Skipper - Erynnis tages
Essex Skipper - Thymelicus lineola
Grizzled Skipper - Pyrgus malvae
Large Skipper - Ochlodes venata
Lulworth Skipper - Thymelicus acteon
Silver-spotted Skipper - Hesperia comma
Small Skipper - Thymelicus sylvestris
Total British species: 58
Total in Gloucestershire: 45
Total number of species seen by me: 35
Number of species seen in my Cirencester garden: 22