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!
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!
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!