It is indeed the old built-up area speed limit. A yellow line on pre-war clocks and white on the later ones.

In the UK at the time, 30 mph was the only speed limit and applied in built-up areas. outside of that was not restricted.

Older Police Officers used to refer to the 'derestriction' marking as the 'GLF' sign - It stands for 'Go Like F*ck'

It has been said many times that Smiffs calibrated their Chronometrics to read 30 MPH when the vehicle was in fact doing 27 MPH hence when in the UK
you will be allowed 10% above before being given an invitation to attend and make a dontation to her majesty's coffers...as a by the way if you like Chronometrics why not try a Bonniksen........ http://www.bonniksen.co.uk/technical.htm
I'm not quite sure I understand the logic of the first post on this thread.....I would have said that there are more bikes that need the speedo's than there are speedo's there are only three/four people in the southern half of the U.K the can repair them.

Hipsters, posers, profiteers, speculators etc. certainly have a heavy hand in this inflation, buying up the instruments for use on bikes that did not come with them originally for their boulevard appeal. Just one more part of this hobby they have ruined.....

I’m not so sure that the Hipsters, posers, profiteers, speculators etc play such a huge role in price. Mostly it’s a supply and demand situation for restorations. Check out the prices of rusty, ratty, busted chronos; still very high and it is for the parts.

It is ridiculous that the set of clocks on a common british bike of the fifties or sixties can be worth most of $1000, 10%-20% of what the bike itself is worth!!

Dont get me started on this! Your quote should be on the mind of every potential basket case buyer. Petrol tank badges, nacelles, sheet metal, switches…….
All that said, there is an art about the chrono that represents the reason we have these old bikes. Clunky, mechanical and works great..I love mine!! Maybe that’s why the prices are high.

Another part of the problem is a lot of people are building bikes up out of bits from Ebay and autojumbles and in the Uk you can get an age related registration for your number plate, this has come about because of the very high prices the genuine and original machine commands you can build a what is a replica out of obtained parts i.e chronometric speedo's and the only way you can tell is by examining the log book this will have the date of first registration.....I have to confess I'm guilty of this I bought a collection of parts that someone was going to build into a Velocette Venom and after two years of collecting and building I have a bike I could never have afforded and it's only ever worth as much as somebody will pay..total cost to build £3500.00 fun factor priceless

bwolfie wrote:http://cgi.ebay.com/ebaymotors/NOS-Smiths-Chronometric-Tachometer-RC-1307-00-10K-4-1-/300536694373?pt=Motorcycles_Parts_Accessories&hash=item45f9620665
a NOS tach

Wierd. Shows a speedo, but if you look below shows what appears to be a refurbished tach unit.

My T110 has a chronometric speedo and I like the clicking motion...its cool. And its got the added 'feature' of the Revulator...... whoopee!!!....a poor mans rev counter.
Currently the T110 is undergoing restoration ..... could be a while....