Ok guys I’ve read all the old stuff on these frames before posting this,just so you know.

But I’ve just bought a load of Bultó bits and one was this frame. In the old stuff it says that this frame  is documented In  Don Morley's Classic Spanish Trials Bikes book on page 40,   Is there anyone out there with this book that could forward the image to me. 
It’s just that what ive read all Miller frames had a number prefixed by SM. 
Ive enclosed an image of my frame number, but not prefixed by SM.
 

Basically is it a Miller frame, or a Whitlock frame or something else.

Many thanks guys.

 

The only difference I can see is that chappo's frame has sidecover mounts that look like M198/199/198A/199A while the photo from the book looks like it would suit something earlier.

Those side cover mounts look homemade and bolted to the same mounts as in the photo

SM Hi-Boy frame. When you refit the engine leave the bash plate bolts just finger tight, tighten the engine mounting bolts, rear first, then the front. Now tighten the bash plate bolts, keep the bolt projections as small as possible i.e. no more than two threads showing. Head steady bracket and bolts should be easily assembled, if not re work the holes so that there is no adverse tension. Some have said that these Hi-Boy frames tend to crack near to the headstock reinforcing plates...I’ve not seen one but then most trials bikes can suffer frame breakages considering what they have to deal with. 

Your frame doesn’t look bad at all and the rust bleed should clean off fairly easily.??

Thanks to everyone who replied, fantastic website.

At least I know it’s a SM Hi Boy.

Lorenzo do you have any text to go with that photo/ image you sent me, looks like there’s a write up with it. Thanks.

Its not for sale, going to be a future project, but what value would you put on one of these frames ??