On day following our trek to Tank Museum my son and I visited a small (but excellently appointed) museum at Maldon (much closer to his home) called the Combined Services Museum (https://cmsm.co.uk) and having expended my inner Nerd store I had to draw on Geek genes reserves which were soon depleted.
Museum is located in an three storey industrial unit within an industrial estate (backs onto an Aldi delivery bay) and looks tad basic from outside however it is a real gem packed literally full of stuff all very professionally presented (pic is of one of a few outdoor exhibits)
Collection based on a private collection that has expanded over the years and covers from BC eras up to contemporary period.
The various display cabinets are chocked full of military items (weapons, uniforms, kit et al) with some larger items.
The building is Tardis like as displays seem never ending, and helpful chap at reception desk (a small counter with some items to purchase) advised that it houses the largest collection of guns in UK which I could well believe.
One starts on ground floor (shocker) with early periods (including lots of ECW) then progresses (mostly chronologically) over its three floors through to Cold War period.
A very interesting section is that devoted to 'spy craft' with lots of SOE and Cold War items with clandestine cameras and weapons and suchlike.
Only real downside is that display cases often close together so with the (ample and bright) lighting it can be hard to avoid reflections in photos (at least with my skill set).
Another highly recommended museum and again I took a deluge of photos of which I offer but a taster/sample selection (hopefully the info cards are legible if pic expanded).