I cannot confirm the date and designer of the cup because there are no markings on the bottom of cup or saucer. But I believe it to be Eleanor Welborn because of the unique type of the the cup handle. The tea cup measures approximately 2.25" x 4" x 3.25" and the saucer measures approximately 5" x 5 x. Both pieces are in good condition showing normal wear for it's age some of the gold has worn off, please see pictures.
The item "Vintage Disneyland Tinkerbell Tea Cup and Saucer with Disney Castle" is in sale since Friday, January 11, 2019. This item is in the category "Collectibles\Disneyana\Vintage (Pre-1968)\Theme Park Souvenirs". The seller is "wanderlustheart" and is located in Westfir, Oregon. This item can be shipped to United States.