I wasn't able to find this apple in any US catalog. Interestingly enough, it originates in Canada. Here's the except from Agriculture and Agri-Food Canada:

"'Diva' originated from crossing 'McIntosh' with the pollen collected from '9AR5T17', a scab resistant line at Agriculture and Agri-Food Canada, St-Jean-sur-Richelieu Research Centre, Quebec. The original cross was made in 1971. Since 1974 the selected seedling, which became the variety 'Diva', was tested for its hardiness, disease resistance, fruit quality, chemical composition and shelf life. After extensive testing it was planted and evaluated in replicated trials since 2000 under the experimental designation SJC7123-1 at Verger du Minot and l'Acadie Experimental Farm."

Don't let the British catalog lure you, you can get equivalent varieties here in the US. A comparable variety is MacSpur, and this is a McIntosh like apple, so other McIntosh related apples will give you similar results. You can also check some of the upstate NY nurseries, they may carry it since it is a Canadian apple and one would think it would have "jumped" the border at one point or another.

Not listed under that name in Fruit, Berry and Nut Inventory - Third Edition (2001, Seed Savers Exchange, Decorah).