The spelling of /b/ is always either <b> or <bb>. Since the letter <g> is associated with two pronunciations, /g/ before vowels <a>, <o> and <u> or finally, and /ʤ/ before vowels <e> and <i> (though not always), we see spellings <gu> and <gh> in addition to <g> and <gg>. I have excluded a few pairs retrieved by the computer which showed the contrast twice, such as bib/gig or reversed in complementary positions, sich as brag/grab.
The contrast is between two voiced plosives, very far apart in the mouth. I have never heard of it being a problem, though mishearings might occur with unreleased final sounds.
One mildly taboo word pair is bum/gum and the contrast occurs in the rhyming phrase "gang bang" for multiple sexual intercourse.
Interesting pairs include
The mean density value is 5%. The list makes 198 semantic distinctions, a loading of 48%.
abbey Aggie abbot agate abbots agates auburn organ B ghee baa'd guard babble gabble babbled gabbled babbles gabbles babbling gabbling babel gable babels gables Babs bags Babs gabs bad gad bag gag bagged gagged bagging gagging bags gags bail Gael bails Gaels bail gale bails gales Bailey gaily bait gait bait gate baited gated baiting gating baits gaits bald galled bale Gael bales Gaels bale gale bales gales balk gawk balks gawks ball gall balling galling balls galls balling galling ball Gaul balls Gauls bally galley bane gain baneful gainful banefully gainfully bang gang bangs gangs Bantry gantry barb garb barbed garbed barbs garbs barbel garble barbels garbles bard guard bards guards Barnet garnet barrage garage barrages garages Barry Gary barter garter barters garters bash gash bashing gashing bashes gashes bass gas bat GATT bate gait bate gate bates gates bated gated bating gating bawd gaud bawds gauds bawdy gaudy bawdier gaudier bawdiest gaudiest bawdily gaudily bawl gall bawls galls bawled galled bawling galling bawl Gaul bawls Gauls bay gay bays gays be ghee beard geared bearish garish beau go beaux goes bee ghee beer gear beers gears belled geld bent Ghent berth girth berths girths Bertie Gertie Bess guess best guessed best guest bests guests bet get bets gets betting getting bey gay beys gays bhang gang bib big bide guide bided guided bides guides biding guiding bier gear biers gears biffed gift big gig bile guile bill gill bills gills billed gild billed guild billy gillie billies gillies bird gird birds girds birth girth births girths blade glade blades glades bland gland blare glare blared glared blares glares blaring glaring blast glassed blaze glaze blazed glazed blazes glazes blazing glazing blew glue blimps glimpse blister glister blistered glistered blistering glistering blisters glisters bloat gloat bloated gloated bloats gloats bloating gloating bloom gloom blooms glooms blow glow blowed glowed blowing glowing blows glows blue glue blued glued blues glues bluing gluing boar gore boars gores boars gauze boast ghost boasted ghosted boasting ghosting boasts ghosts boat goat boats goats bob bog bobbed bogged bobbing bogging bobs bogs bobby boggy bode goad boded goaded bodes goads boding goading bodice goddess bodices goddesses bold gold bole goal boles goals Bonn gone boo goo booby boogie boobies boogies boon goon boons goons bore gore bored gored bores gores boring goring bores gauze bought ghat bound gowned bourbon Bergen bout gout bow go bowing going bowl goal bowls goals bowled gold brace grace braced graced braces graces bracing gracing brae gray braes grays braid grade braided graded braiding grading braids grades braille grail brain grain brained grained brains grains braise graze braised grazed braises grazes braising grazing brand grand brass grass brasses grasses brassy grassy brassier grassier brassiest grassiest brave grave braves graves bravely gravely braver graver bravest gravest bray grey braying graying brayed greyed brays greys brays graze brayed grade brazier grazier braziers graziers breed greed breve grieve breves greaves brew grew brief grief briefs griefs brill grill brim grim bristle gristle broom groom brooms grooms browned ground brunt grunt brunts grunts buhl Goole build gild builds gilds builder gilder builders gilders building gilding built gilt built guilt bum gum bummed gummed bumming gumming bums gums bunny gunny bun gun buns guns burble burgle burbled burgled burbles burgles burbling burgling burgle gurgle burgled gurgled burgles gurgles burgling gurgling bust gust busts gusts but gut butt gut butted gutted butting gutting butts guts butter gutter buttered guttered buttering guttering butters gutters buy guy buying guying buys guise buys guise by guy bye guy byes guys byes guise cob cog cobs cogs Corby corgi crab crag crabbed cragged crabs crags dibber digger dibbers diggers drab drag drub drug drubbed drugged drubbing drugging drubs drugs dub dug dubs dugs ebb egg ebbed egged ebbing egging ebbs eggs fab fag fib fig fibs figs fibber figure fibbers figures fob fog fobbed fogged fobbing fogging fobs fogs gab gag gabs gags gabble gaggle gabbles gaggles garble gargle garbled gargled garbles gargles garbling gargling gibber jigger gibbered jiggered gibbers jiggers gobble goggle gobbled goggled gobbles goggles gobbling goggling hob hog hobs hogs hub hug hubs hugs jab jag jabbed jagged jabbing jagging jabs jags jib jig jibbed jigged jibbing jigging jibs jigs job jog jobbed jogged jobbing jogging jobs jogs jobber jogger jobbers joggers lab lag labs lags lob log lobbed logged lobbing logging lobs logs lubber lugger lubbers luggers nab nag nabbed nagged nabbing nagging nabs nags nibble niggle nibbled niggled nibbles niggles nibbling niggling pub pug pubs pugs rabid ragged rib rig ribbed rigged ribbing rigging ribs rigs robe rogue robes rogues rub rug rubs rugs rubber rugger shabby shaggy shabbier shaggier shabbiest shaggiest shabbily shaggily shabbiness shagginess shrub shrug shrubs shrugs slab slag slabs slags slob slog slobs slogs slobber slogger slobbers sloggers snob snog snobs snogs snub snug snubs snugs stab stag stabs stags stabber stagger stabbers staggers tab tag tabs tags tub tug tubs tugs upbraid upgrade upbraided upgraded upbraiding upgrading upbraids upgrades
John Higgins, Shaftesbury, January 2010.