Just leave it alone to do its thing - you should get more blossom in spring. Spring this year was warm early and cold later, so a lot of fruit trees were not pollinated because the flowers were damaged. I've just tried to check whether this tree needs another for pollination purposes, but am unable to find any variety called 'Howden Wonder'

It might be Howgate Wonder? I have that one, in fact, it's the only apple tree I have got! Worthy

If it is Howgate Wonder, it's only partially self fertile, so a pollinator nearby would give better results.

If you type the correct name of your cordon apple tree into Google search + pollinator you will find sites that tell what are the best pollinators EA. I have a small apple tree that won't even make blossom so I have planted a small height clematis to grow up it. It is early days, anyway, if only planted October one year ago. It certainly is weird for it to blossom now......silly tree! If you have a row of cordons , as we used to, and have accurate names, one of them may be a good pollinator; and save the expense of jumping too soon to the idea of the tree not performing well.

Thanks you to all, it is indeed a Howgate Wonder which on the label said it was self-fertile. I do have a cordon Cox's Orange next to it. Will have to wait & see what happens next year. :)

Howgate Wonder's pollination group 3, so you need something in Group 2 or 3 as a pollinator - Cox's self fertile would work, not too sure about Cox's orange though. If you have other apple trees nearby in other gardens, or a crabapple nearby, they should work as well.

By the way congratulations on using this brave apple blossom as an Avatar! Made me feel a bit more cheerful.....but not a lot.