Late Payment Not Showing On Report

Hi,

I have recently applied for a mortgage and they have came back to be asking for details on a late utility bill payment in Jan 2016 that showed on my credit report.

This blew me a way, as I wasn't aware of any late payments.

I have checked all 3 reporting companies (Equifax, Experian and CallCredit) and none of them show any late payments on both opened or closed accounts.

The only thing I could think off is after moving into my first flat I waited to move gas/electric supplier as I was initially told from my landlord that they would inform the utility company of my details (Lesson learned - do it yourself, right away!).

The remaining balance was paid off as soon as I found out that there was an outstanding balance on the flat.

Checking my report the mortgage provider done a hard search.

Will this give them access to more detailed information than what I can get? Struggling to see where the late payment came from

Thanks!