Sorry to revisit an older thread but I'm new to the forum and I just thought I'd tell you about your Bren.
Its a Lithgow (Australia) Mk1 pattern B gun which has been (Or after 1942, built as) modifed to Mk1 upgraded standard with a unique to Lithgow Mk3 type bipod ( A hybrid of the Mk1 bipod legs and the feet of the British Mk2) and a Mk2 barrel which is a copy of the Canadian Inglis Mk2 barrel (Not the British Daimler/monotype Mk2 which is different).
Lithgow made the smallest number of Brens of any manufacturer, approx 17428 guns making them numerically rare but as most were imported into the UK in the 1990s, there are plenty around. Regarded as a entry level Bren, many collectors snub them but I find the Lithgow offers the best value for money. I picked up my unissued 1943 gun in box with mag box, sling, cover and tools for 145 about 8 years back, I wish I'd bought more!
If your intrested, let me know the serial number and I'll give a appox production date.
ATB, Chris.