About the only thing thriving in our garden at the moment, apart from a few slowly swelling squashes, are the leeks. It set me thinking about the possibilities of preserving them.

Not being able to find any recipes that weren't for something more like a relish, that would only last a few days in the fridge, I posted some queries on the several forums.
This raised some interesting thoughts:

TwoSheds on growfruitandveg.co.uk thought that the end result would be slimy.
Stupo74 on vegetable-gardens.co.uk found a welsh leek chutney for sale. Zigzag at allotments4all.co.uk made the very good point that there is really no need to preserve leeks as they last in the ground so long.

I thought I better take this through to it's conclusion and try out a recipe, just to see if it was possible, although I was pretty won over by zigzag's point.

Having recently made onion marmalade, I reasoned that since leeks aren't dissimilar to onions a variation would on this recipe would be a good start.

  See here for the leek marmalade recipe.

Recipe Costs

£1.19 600g leeks (equivalent cost, mine were free)
£0.40 250ml vinegar (cider or white wine)
£ 0.42 450g granulated sugar
£0.79 3 sprigs of rosemary (equivalent cost, mine were free)
£2.80 Total (£0.82 without buying the leeks and rosemary )
£5.60 per kg of marmalade (£1.64 per kg without buying the leeks and rosemary - 17.5% of the cost of equivalent at chefontherun)

In order to minimise any excessive sliminess I chopped the leeks quite thinly.

The sugar is dissolved in the vinegar...

... and then 3 sprigs of rosemary added in a muslin bag. I had decided that leek and rosemary might be a combination worth exploring, reminiscent of roast dinners and a leek and rosemary pizza I had at pizza express about 20 years ago.

The marmalade only needed simmering for about an hour and a half before it was thick enough to pot up in steralised jars.

The recipe made about 500g of dark marmalade.
The leeks didn't break down much during the cooking, but went some translucent and some retained their green colour, so it looked quite interesting.

Recipe Timings

15 mins preparation
1.5 hours simmering
15 mins potting

Taste Test

Sweet,with a  slight hint of woodiness from the rosemary. The leek taste comes through, so definitely a different preserve to onion marmalade.
The problem I have with this preserve is (as predicted) the texture of the leeks, not actually slimy, but quite fibrous. This means that the occasional bit needs a good chew, and whilst doing so squeaks between your teeth.
On balance I would recommend that onion marmalade was probably a better use of the basic ingredients.