The spelling of /g/ is <g> or <gg>, but we also see <gh> in ghee and <gu> in league . The /ʃ/ sound is spelled <sh> or <ch> in the loan words chaise and chauffeur.
This is a contrast between a voiced stop and a voiceless fricative, well separated in the mouth. It does not cause any problems.
The only taboo word pairs are gag/shag and gat/shat.
Interesting pairs include:
The figure for the mean density is 2.6%. The set makes 89 semantic contrasts, a loading of 57%.
Aggie ashy bag bash bagging bashing bagged bashed bog Boche brag brash clog cloche cog cosh crag crash dig dish digging dishing fig fish figure fisher figures fishers flag flash flagging flashing gateau chateau gateaus chateaux gad shad Gael shale gale shale gag gash gagging gashing gag shag gagged shagged gagging gashing gags shags gal shall gallows shallows gamble shamble gambled shambled gambles shambles gambling shambling game shame gamed shamed games shames gaming shaming gammy shammy gape shape gaped shaped gapes shapes gaping shaping gassy chassis gat shat gaud shored Gaul shawl Gauls shawls gauze shores gave shave gays chaise gaze chaise gazes chaises gear shear geared sheared gearing shearing gears shears geld shelled Gertie shirty ghat short ghats shorts ghee she gift shift gifted shifted gifting shifting gifts shifts giver shiver givers shivers go show goad showed goal shoal goals shoals god shod godown showdown godowns showdowns goes shews going shewing goings showings gold shoaled goo shoe gopher chauffeur gophers chauffeurs gore shore goring shoring gored shored gores shores got shot gout shout Greek shriek Greeks shrieks grew shrew grill shrill grilled shrilled grills shrills grilling shrilling grind shrined grove shrove grub shrub grubs shrubs guard shard guards shards guide shied gun shun gunned shunned gunning shunning guns shuns Gurkha shirker Gurkhas shirkers gut shut guts shuts gutting shutting gutter shutter guttered shuttered guttering shuttering gutters shutters guy shy guyed shied guying shying guys shies hag hash hug hush hugging hushing hugged hushed Josh jog lag lash lagged lashed lagging lashing league leash lug lush lugger lusher mag mash Meg mesh mug mush muggy mushy muggier mushier muggiest mushiest nag gnash nagging gnashing plug plush rag rash rug rush sag sash slag slash slog slosh slogging sloshing slogged sloshed slug slush stag stash swig swish swigging swishing swigged swished tog tosh Whig wish wig wish wigged wished wigging wishing
John Higgins, Shaftesbury, October 2010.