Alan
I expect the aircraft you saw at Southend was VH-XBA formerly VH-EBA:
VH-EBA
JT's aeroplane is the former VH-EBM which had a nosewheel collapse at Luton on 28 March 1977 while operated by Tracy Investments as N108BN.
VH-EBM
There were only 13 B707-138s built and thanks to JT's generosity Australia will now have the first and the last as perfect bookends.
Does anyone have any local knowledge of the NLG collapse at Luton?