identifying the lockshield valves

[warehouseman]

Recently acquired a property which has had an additional radiator installed.
System needs balancing - I am familiar with the technique to do this. However some of the other radiators' caps have been taken off. There are a few radiators where the valve at each end looks exactly the same !
How do I distinguish the difference between the 'lockshield valve' and the usual heat adjustment valve ?

 

[HarrogateGas]

It really doesnt matter which end you use as a lockshield.

 

[gas4you]

Turn the system on from cold and the pipe that heats up first will be the flow on/off, therefore other end will be lockshield.

As Harrogate says though it doesn't really matter