Overly parochial, Denis
The next appearance of a BT4 after Caversham was at Pukekohe and Wigram(NZ) where Brabham again drove IC-1-62
My period notes say Brabham's Warwick Farm (etc) car was IC-3-62 and Stillwell's IC-2-62, though the latter was identified as FJ-11-63 (not 62). I know the Stillwell car is plated IC-3-62 today, so I am quite prepared to believe I was (am) mistaken. How do we know the numbers you quite are correct?
Comments on your later histories:
IC-1-62
After Scuderia Veloce to Lesco RT in NZ, who were Grant's entrant. Also driven twice by Neil Whittaker in Lesco colours before returning to Australia and John McCormack
IC-2-62
assuming for these purposes that your numbering is correct
Brabham 1963 Australian internationals, Hulme 1964 Tasman
John Coombs was owner in 2000 but I think Frank Sytner bought it from him. Either way, I believe it is now in the US
IC-3-62
Your NZ ownerships are a bit askew
Sold by Stillwell to Thomasen, then Ecurie Palm Court (drivers Ian Green, John Riley, Robbie Franicevic). Then Syd Jensen (driver Jim Boyd). Then Faloon. Pre-Glasby owned was Richard Hook
In UK, car passed from Harper to John Beasley 1998 and Alan Minshaw 2004
I believe there was a fourth BT4, Vögele's Swiss hillclimber (IC-2-63) though I have that number allocated to two BT7As. I'm sure Allen will quickly straighten us out on this