Ditch Stitch Guide

I picked up my sewing machine from the repair shop yesterday. It's been serviced and has a new foot control. I'm looking forward to testing it out. Nick, who I've mentioned is crazy keen about old sewing machines, was his usual enthusiastic self. I took the opportunity to ask him about a clever presser foot I'd seen one of my students using. She called it a "ditch foot" but that didn't ring any bells. Rather than just a straight "no" though, the conversation continued. I grabbed a pen and paper to sketch out how I thought the thing worked. Then Nick grabbed several drawers full of presser feet and started rattling through them, picking up one foot after the other until he came up with this:
It's a blind hem foot--as it turns out, I had one a lot like it in my work box which I'd never used. The relevant detail is the little vertical ridge which you can just see in the lower right of the pic. That works as a guide to keep the stitch line straight against a fold of fabric. In my case, I'm hoping it will keep the stitch line along the ditch where the seam allowances are folded away. I'll have to try it out. My blind hem foot had an extra little horizontal piece which, though fine for blind hemming, would probably get in the way of my quilting, so we swapped. Since I wasn't using mine anyway, I'll either be in the same boat as before and keep looking for the elusive "ditch foot", or my problem will be solved and I'll have a new tool to help me with my quilting. I guess that means I'm going to have to do some quilting today.