Why is this bridge being demolished?

We have just hurried past bridge 15 on the North Oxford as BW are closing the canal for ten days from May 9th to allow Punch Taverns, who apparently own the bridge, to pull it down.
That gives rise to many questions.

How does a pub company come to own what looks like a normal canal bridge and, as such is part of the historic structure of our canal system?
Why are they allowed to pull it down - shouldn't it be protected as an historic structure?
As BW admits it has been in a bad condition and dangerous for some time why have BW bosses allowed it to get to the stage where destruction is claimed to be the only option?
Even if that is the case, why wasn't this done in the stoppages season and why is a third party allowed to close a busy canal in the boating season - and for 10 days?
Why haven't BW insisted this bridge is repaired? Could it be because they have problems looking after other bridges on the same canal?
This is bridge 80 on the same canal and it has been in the same state for several years.

Any chance of some answers?