Mine produces fruit without any help from me, but all the dried fruits have immature seeds in them. Do a google.com search on how to pollinate Passiflora 'Lady Margaret'.

FIrst try selfing it. Just pull off an anther and use it to apply the pollen.Pollinate most Passifloras as soon as they open. Using pollen from whatever parents were used to create the hybrid might be more successful. Finally, The fruit may not be good enough to eat and probably will not make identical plants of 'Lady Margaret'; certainly you cannot call them 'Lady Margaret'.