240Vac LED Off-Peak power flicker
As @user253751 says - it sounds most like the effects of ripple control signals  - high frequency tones used to turn off and on hot water heating and other low priority loads. 

Even if it IS ripple control related - it MAY be an interaction between bulb, signal and dimmer. If you place one of the new bulbs at a location where the other LED bulbs do NOT cry out to you, does the effect persist. 

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Here are some Australian sources of ripple control filters - and DIY with off the shelf components may be feasible. Also, local electricians should be aware of the effect if it is ripple control related. 

Google search here

Here  is a purpose designed $75 Australian solution. Hunter Pacific 
ZF-1050 Notch Filter Noise Suppressor



This is far far far too dear for what's inside - but may help. 

Note from here 


" ... The ripple control filter must be matched to the local signal being output by your electrical company, usually 750Hz or 1050Hz (information of which can be acquired through your electrical company), and must be installed by a licensed electrician.  
There may be extreme cases where the ripple control frequency is so strong it requires two filters to be installed to reduce the noise sufficiently and in some locations multiple ripple control frequencies are used also requiring multiple filters. ... "


Useful comment on page 14 here - related to fans but probably relevant


Throughout Australia, but in particular Sydney ... NSW ... , electricity distributors use a remote control and switching system that is commonly called ripple control. ... Ripple control systems superimpose signals on the 50 Hertz mains  ... Electrical equipment such as televisions, toasters, fans, fluorescent and halogen lighting and some appliances may be sensitive to ripple control signals. This results in an audible buzz being generated whenever the signals are present. As different frequencies for these signals are used in different areas, products may respond is some areas and not others. Some areas have more than one ripple control system in operation and different signals may be present at different times and affect different products."
Also: " ... In areas that have ripple control installed for off-peak tariff switching (such as off-peak hot water systems) there is
usually a dual tariff meter installed, or dual meters. A smaller control box marked “Zellweger” may also be present. The
meter or Zellweger box will usually have the ripple control signal frequency marked on it (for example 1050 Hz)."


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It's likely DIY enthusiasts will have established components suited to ripple control filtering. A suitable series inductor (maybe a fluorescent light ballast) and a suitably rated across-mains "X" capacitor of the right values may well be adequate. Off the shelf components designed for residential mains installation are available. 

Another possible solution (YMMV) is to use a suitably rated 1:1 ration "isolation transformer" to feed the lighting circuit. This may  work by itself or with a following across mains X-rated capacitor. [ Capacitors connected across mains phase to neutral MUST be rated for such service. X-rated caps (a real term :-) ) are intended for this use. ]