Is there a guide to this form of notation?

[Benjamin Mortimer]

I am looking through the scores section of the site and am unfamiliar with this style of notation

Is there a name for it and a general guide anywhere for beginners? 

I can see that it must be traditional due to finding it in the "Princess Anne Lute book"

[Monica Hall]

It is French lute/guitar tablature. James Tyler's book "The guitar and its music" O.U.P. 2002 has a section on reading tablature and so does his tutor "A guide to playing the baroque guitar" Indiana University Press 2011. There are other lute tutors etc. which include the basic notation. You may be able to find something on-line.

[Edgar Aichinger]

There used to be a short introduction to reading tab at Wayne Cripps' Tab site, but it seems to be gone; luckily the wayback machine saved a backup in 2019, here:

Introduction to reading lute tablature

This covers the basics for understanding renaissance lute tab (french and italian system) - I am aware that the example you posted is baroque guitar tab, not renaissance lute, but it is in fact the same system. Lute tabs employ a sixth line and letters below that for additional bass courses.

This system is very practical, as you don't have to translate absolute pitches to positions on the fretboard - it simply tells where to put the fingers at which point in time, and as long as the tuning of the instrument matches the one the tablature was meant for, it will sound right.