Hi, I have now sussed out that yellow plant, it is indeed a primrose, a Missouri Primrose.
My greatest delight is seeing this plant flourish from a seed that I planted myself.
Here is a glimpse of my Shark's Fin Marrows, the bees are busy but it is a gamble on them polinating because over two dozen female blooms and only three males < each opened on odd days. The blooms last about 24hours and then they closed up. Once closed up, the female flower will start to die if not pollinated. I have tried to polinate fresh (just a few hours) closed female blooms and these too have died. So I have learnt that you cannot 'rescue' these fruits and just have to have a good moan at the SLOWNESS of the male blooms!
<<<<< All 3 are female because there is a bulb attached to the flower. Lily