James- your plant is a hybrid. It is half walkeriana var alba and half Laelia superbiens var alba. Your tag has the spelling of superbiens wrong. That is what your tag says anyway and I can tell by the size of your plants pbulbs and leaves that it isn't a pure walkeriana. C. walkeriana plants are smaller than your plant. C. walkeriana is fragrant and the Laelia parent is suppose to be fragrant too. I just looked online and I guess L. superbiens spikes grow from the top of the pbulb. The plant should be white since both parents are var alba. C. walkeriana does grow its spike from the rhizome but they can grow from the top of the pbulb too. My walkeriana var alba 'Pendentive' usually blooms from the top of the bulb. Since yours is a hybrid it probably will spike from the top of the pbulb. I have never heard of 'Pendentive John' before and I couldn't find it when I Googled it. Laelia superbiens also comes up as Schomburgkia superbiens. Here is a photo of L. superbiens var alba.
IOSPE PHOTOS Here is a picture of C. walkeriana var alba 'Pendentive'.
Cattleya walkeriana var. alba 'Pendentive', AM/AOS at Santa Barbara Orchid Estate When your plant blooms please show us a pic. I'm curious to see what this cross will look like.