Is it root bound? I have seen this behavior in potted plants even in the hot south that i live in? Years ago when we lived in an apartment, my curry leaf plant did the same. Once I put it in the ground in our house it took off. Now I have little seedlings all over the yard.

I got seed from an acquaintance in Hawaii. Contact growers in Hawaii and Florida - possibly some in CA as well - to see if they will ship you seed. There are restrictions on where/how seed can be shipped because of citrus disease - if you are in a citrus growing state, look for seed locally as M. koenigii is a citrus and is likely grown in any state where other citrus are grown. My seed arrived already cleaned of the fruit pulp, and in moist peat moss to keep it from drying out. Dried out seed is unlikely to grow, it is very fragile and short-lived. I planted my seed in 2" starter paks (2" diameter, not depth). These need to be kept warm and moist, but not wet. Use a seed mat if possible set at 81 to 82F - they like 80F but most seed mats come with controllers that shut off within 3 F of the target temp - so my seed mat was turning off at 77F. I never saw it shut off too late, but it often shut off too early. If you have a herp controller, those are MUCH more accurate and you can just set it at 80F. ALL of my seed eventually germinated. Germination was faster while bottom heat was applied. You should probably remove the plant from the bottom heat soon after it sprouts - so use smaller paks, like 4 cells, or even individual pots. I ended up cutting my starter paks up because they were full-flat paks, with something over 30 cells. Beyond that, I can't say how to best care for your seedlings. I'm still learning. I tried putting them in a gritty mix and a modified gritty mix - the modified gritty mix took longer to fail than the gritty, but it did eventually fail, despite all sorts of contortions (and with the help of a local soil scientist) trying to correct for pH and trying to find a way to water the gritty that didn't leave dry streaks through the medium. The only plants that did really well were those planted in the usual peat blends. Between the watering problems (I had to float my gritty pots to get them thoroughly watered, and they dried out FAR too fast in my arid environment) and pH induced fertility problems - foliar feeding with Foliage Pro did NOT counteract these issues - gritty and gritty-ish were both ultimately unsuitable for these plants. They were particularly troubled by iron deficiency problems, despite regular application (for half the plants) of iron. This made very little difference because it just runs out of the gritty mix. Foliar feeding of iron solution also did not make a noticeable difference. So I suggest sticking to a good bagged potting mix, or a good peat blend once your seedlings have sprouted. A palm blend and a palm or citrus fertilizer is probably best. Watch for iron deficiency - M. koenigii is a heavier than usual user of iron.

Can any one please tell where I can get Murraya koenigi seeds or seedlings in the UK preferably London? Many thanks

In my experience curry leaf tree does VERY poorly in direct sun. it is grown in the "understory" in India because that is where it grows naturally. I LOVE the smell of the leaves! I love cooking with curry leaf. Mine are in fabric pots in a medium of Growstone 2 and peat moss, topped by bark mulch to keep the Growstone from floating up. I had them in a gritty-like mix that did not work for them at all. The survivors of that experiment are also in the Growstone/peat medium now. All the plants that were originally planted into the Growstone/peat mix are 2 to 5 times larger than the others - the longer it took me to get them out of the gritty-like, the smaller they are (plus the last of those died before I could repot them). The largest plants, which were in Growstone/peat from the start, are flowering now. I hope to harvest some seed and start some more, but I'm not holding my breath. They REALLY need to be fertilized - I should have hit them with some iron last year and didn't get around to it, now they're recovering from that shortage. I put them out yesterday because it was supposed to be 55F last night (I never put them out unless the night time temps are above 50) and when I woke up this morning it was 42F. Drat. So I may get blossom drop instead of fruits, LOL! Growstone is allegedly pretty alkaline, my tap water here is about 9, and peat is pretty acidic. They get along OK anyway. I have no idea what the needs of the plant are because I have never been able to find anyone in the US who knows anything about them. Except that they need more iron than most plants (hence the iron supplementation which should happen at least every couple of years but hasn't happened but once since I planted them). I've been told to use Palm fertilizer on them but I usually just use Miracle Gro every couple of years, or a JOB plant spike or 3. Plus the extra iron supplementation. They are tolerant of drying out. In the Growstone/peat mix winter before last, I was very ill, and they didn't get watered for about 3 months. I lost several of the remaining gritty-like plants but all the Growstone medium plants were fine. That medium REALLY holds the moisture, without ever getting waterlogged. Since then the last of the curry-leaf tree in the gritty mix have died. They just didn't do well in that mix. But everything in the Growstone are still doing OK. How big is your plant? I'm not sure what kind of information you are looking for. Pretty nearly everything I know about M. koenigi is here: https://www.gardenweb.com/discussions/1843090/potting-medium-for-citrus?n=15