Hi there. Not sure why you can't find much info...? I just did an internet search for 'pruning passion flower' with great success, and the RHS's invaluable pruning tips were right at the top of page 1.

Since it is a bit wild looking and you want to make your frontage more pleasing to look at, the time to take action is now rather than waiting for the end of the growing season. Trim it back about a third shaping as you go. Sure, you will loose some flower buds but it had to be done and next year you can prune at the appropriate time. Of course start pruning from the periphery in.

You can cut it back to 1-2 feet above ground level if you like - it'll regrow. If its the basic, hardy one, in cold winters, they get killed back to the ground, so pruning often isn't necessary, but as yours is somewhat untidy, do it now, it'll still flower, but probably later. More info in the link below

https://www.rhs.org.uk/advice/profile?PID=295

Thanks everyone for your help.

Just a quick update on this question. Last year it died back for no clear reason but this year it has come back with a "vengeance"! It has had 100s of flowers, but no fruit!

He has now got to leave the house & would like to take it with him but he can't being as it came with the house when they rented it 3 years ago. As there are no fruit & therefore no seeds, can he take some cuttings of the branches NOW?

There is some information under propagation in the RHS link previously provided above.

Thanks, once again, Bamboo! I should have looked at the RHS page earlier.