Hi Fox
I used to know a few Leyland/Morris mechanics in Bunno but they will all be retired or dead by now.
When I had my Morris we used to put a little bit of air pressure in to the fluid reservoir with a small compressor with the bleed screws opened one at a time to force the fluid thru -
Just crack the bleeder on one wheel and give it some air pressure - best done with 2 people -
You only want a little pressure or you will blow the cap off and get a face full of fluid - a bike pump might even be enough -
Keep an eye on the fluid level as you go -

You can also grab an "OLD" bike pump, the long skinnyone - mod the end so it will take some fuel hose and suck brake fluid up inside it.
place the fuel hose over brake bleed nipple and force the brake fluid backwards thru the system - watch for overflow -