Return Location of Alpha/Numeric String

Hello,

How can I formulaically find the starting location of a string that is letter + 6 numbers + letter in a longer string?

As in,

Find 'a123456b' from po34ksa123456b95043, with an answer of 7.

I was thinking FIND() with wild cards, but the wold cards would have to specify whether it was text or numeral. Any help appreciated!

Greg