After searching extensively I have been unable to find a name for this plant. It was found growing in the Eden Project Tropical biome in the UK. The flowers were approximately 7-8 cm across. Any help greatly appreciated!
After continuing to search I have located the name of this plant. It is Ipomoea alba or 'Tropical white morning glory'. On locating the area of the Biome on a map where I had found it, I could conclude it grew in tropical and sub-tropical areas of South America and north of there. This narrowed down the search somewhat. Thanks again to all involved for helping to identify!
They seem to closely resemble the shape of the "Golden Chalice Vine" (Solandara Maxima). Although they are a more yellow color and their leaves fold outward rather than inward, it is entirely possible that the flowers you found were still in the process of fully blooming.
I also found a it growing in the Eden Project Biome you mentioned, here is the link to the plant page on their website: http://www.edenproject.com/learn/for-everyone/plant-profiles/golden-chalice-vine
And for some more pictures and information: https://toptropicals.com/catalog/uid/SOLANDRA_GRANDIFLORA.htm
Hope this is the plant!