Yea everything is 1/8th. Cog and chainring are basically brand new (sugino messenger chain ring and soma track cog) I’m thinking a new chain is the solution.
Are Soma cogs “extra chunky” like Surly cogs are? If yes, then a 1/8" KMC 510 won’t be wide enough, but a Kool chain will be fine.
Never judge a shop by it’s cover. What is lacking in a big wanky shop front and crabon NuFred stupidness is more than made up for by the fact it is a bit of a gold mine. They have all sorts of amazing gear and always give you a good price. Well worth going in and asking for what you want cos likely as not it won’t be on display due to the size of the shop. Also check out some of the vintage stuff the old geezer has hanging up - a 50’s Bianchi.
qft.
I just turn the volume up on my ipod up whenever my chain’s fuked and noisy
i just leave mine at blakey’s and wait for him to be so disgusted he cleans my bike and helps me replace the chain in question… 
…and don’t overlook creaky nipples. Had one of my bikes apart several times before discovering creaky nipples were the culprits…
…and then there was the time it was creaky saddle rails…
…and then there was the time when it actually WAS my chain.
So went into cycles bespoke in bayswater and picked up an Izumi chain. Took it home and realised it was a 3/32 not 1/8. Dude in the shop upgraded me to a gold Izumi for free 
smooth as butter now. The rollers on the old chain actually had so much play front to back…
First day with new chain and bike gets soaked on the ride home. Anyone recommend any particular chain lube for wet weather use?
^this is the shizzle!!!
never bought off cell bikes before. They have fast postage etc? This chain lube looks the goods
Cell Bikes are most excellent.
Party on, Garth.
look out for the royal ugly dudes