I don’t know about pensions but the Empire recognized certain cities as “Colonias” which were retirement centers for legionaries and were provided with a higher level of public services than typical Roman towns.
Sometime before Rome abandoned England during the Boudica led uprising a Colonia was attached and the retired legionaries were all slaughtered.
Boudicca was a genocidal c-word, and wound up demagogue-ing her fellow bloodthirsty moron tribesmen to attack the Roman governor, who'd carefully chosen the battle site to his advantage. Roman losses were small, the c-word died along with 70 to 80 thousand of her followers.
The Romans then ruled Britain for another 350 years.
It would be nice to find the real actual one and only site of the battle. I suspect the captured British survivors were tasked with finishing their own wounded and then incinerating them in one great pyre. 70,000 x perhaps 32 teeth could mean, a great pile of surviving teeth (2 million) and that suggests a pretty good supply of testable DNA.
The Iceni capital was replaced with a grid style Roman colonial town. Literally no trace of the original has been found, my guess is, it was never any great place, and then the B led them to extinction / slavery, and the Romans just erased all trace before building their colony.