Im really stuck - Ive just bought every pen Asda do and none of them will write on the back of a photo. Anyone know the best sort to use?

A fine-tipped permanent marker?....

The photos are £1 a pop, I need to be sure man, I need to be sure. A marker would do but I dunno where to get a super-fine one from.

Poor quality ones will probably bleed through over time.  Try your local art shop.  Theres a good one in the top-end of London Road, Hilsea... I forget the name.  8-)

In theory you should ba able to get one from any decent stationary shop....maybe even WHSmiths

Sorry, but what about a pencil?

Could always use the permanent OHP pens? They seem to write on pretty much anything and dont really bleed?

I used a parker pen in the end and it worked nicely : )

Steadtler Lumocolour permanent markers available in very fine sizes, ideal for that.

http://www.staedtler.co.uk/Lumocolor_permanent_universal_pen_au.Staedtler?ActiveID=28658[/img]

If you want a nice finish then stick some adheasive address labels through a printer and stick them on...