The right at any time or times prior to the expiration of a period commencing on the 22nd day of December 1920 and terminating on the 20th anniversary of the death of the last survivor of the issue now living of Her late Majesty Queen Victoria to make connection with all or any of the part of the hereinbefore mentioned storm water drains and sewers ...
The questioner hadn't seen time limits defined by the lifetime of royalty before. The answer turned out to be
This is an attempt to escape the rule against perpetuities.
"No interest is good unless it must vest, if at all, not later than twenty-one years after some life in being at the creation of the interest."
...Because royal families are large and wealthy, the likelihood of one of them living ...(a long time)... is large.