"I.G.S." wrote
I planted my Campsis Radicans seven years ago. It is sited on a corner
of my house in Wiltshire in fairly light soil on green sand where it
gets full sun for at least eight hours per day during the summer. It
puts on terrific growth every year, eight foot on a trellis, then
clinging to the wall ( or trying to) up to a height of fifteen feet
plus. At the end of the season I cut it back to the top of the trellis.
It has never shown the slightest inclination to flower. I thought I had
over-fed it so have not done so for four years though it may pinch some
food from a neighbouring rose. The only other plant of this type that I
have observed appeared to be pruned severely every year. Any
suggestions?

This is your problem..."At the end of the season I cut it back to the top of
the trellis".
This plant is no good for a tidy gardener, in order to flower branches need
to move in the breeze so pruning it in autumn/winter to keep it tidy is a no
no. Perhaps the owner of the other plant prunes theirs at a different time,
just after flowering maybe, so it can make new waggly branches for flowering
the next year.
I would also use a tomato feed late summer to encourage flowers, and
certainly not a high nitrogen one.

--
Regards
Bob Hobden
W.of London. UK