The locking bar would move only slightly, perhaps 2-3mm and usually spring back to resting position, if you turn it you can feel the spring resisting your turn of the key then chances are it is a detector.
A detector is a feature patented by Chubb in 1818 and it is a device contained inside the lock to prevent picking the lock and if someone was to either try to pick the lock or insert the wrong key then the lock would stop working notifying the owner that someone had been tampering with his lock, the original key wouldn’t open the lock until it is reset by turning the genuine key in the locking direction thereby dropping the detector lever back to operational condition, the nice feature of the detector mechanism is that if the picker tripped the detector then he would never be able open the lock regardless of how hard he tried or how long, once the detector is tripped then it is near impossible to open it without the correct key without destroying it, the only way for someone to reset the detector without the key would be to pick the detector reset gates and then try to pick the lock again risking another detector trip thereby informing the owner.
If you wanted to sell it you could try Ebay, that way you would get a wider audience and get the collectors price, Antique locks are a limited market so you will get collectors mostly who would generally push up the bids to the proper value, now is not a good time to sell it, if you want my advice sell it around the first 2 weeks of April or May when people are off work to get the greatest audience, if you want a starting price aim for £100, if you want the greatest interest then £50.
Peter can be contacted through this site —> http://www.chubbarchive.co.uk/ Please browse and read the pages to become better acquainted with the history of Chubb and the Detector Lock, we as a community would value a little time to read Peters website, it is a great source of information on Chubb and perhaps the best on the net.
Peter would be the best person to ask any questions regarding anything about Chubb
Regards
Kit
