Sunday Times Teaser 2776 – Winning Months

by Graham Smithers

In winning three Premium Bond prizes, I noted the numbers of non-winning months between the first and the second and between the second and the third.

I also noted the difference in the lengths of month names between those of my first and second wins and between those of my second and third wins.

All four numbers were the same and, if you knew this number, you could then work out the months of my wins.

What were these (in order of the wins)?