Pic's a bit out of focus, so can't see detail of the leaves, but it vaguely resembles a Euonymus japonica variety, although usually, the leaves are not all yellow, there are mixed green and yellow leaves and plain green leaves. You sure its just popped up? Looks more like something's been cut down and has just started to grow again, judging by the number of leaves and stems - seedling growth wouldn't be so far advanced, unless it was there last year too. Otherwise,this is just an educated guess, since the picture does not provide clear detail.

It does look more like a stump sprout, probably from Euonymus japonicus 'Aureomarginatus'. As an unstable chimaera, it often reverts to a nearly albino state, with just enough chlorophyll in the older leaves to support itself.

I’ve been doing the garden 10 years, and not cut anything down in this area, it’s come up under a rubber tree next to a pomegranate tree, only thing I’ve added is well rotted horse manure and Home made compost.

Interesting then - if its brand new this year, must be something rapid growing as its this size now, when did you first notice it?

I would concur as it being Euonymus, probably 'Green and Gold'. It could be self-seeded and produced a 'sport'. Bare in mind that it will germinate very quickly in the Spanish environment. Could be that it was propagated as a bird dropping from a berry.

Thanks guys looking at old photos I did have a green and gold shrub furthur down the garden that I took away 2 years ago, could it be seeds from this?

Yes, could be... but I still think its Euonymus japonicus or a sport of, not a Euonymus fortunei variety - the former makes a tall fairly upright shrub, whereas the latter grows as wide or wider as it is tall, usually around 2/3 feet tall. Its just the upright appearance that makes me think its E. japonica - be great if it all remained bright yellow, its very striking...

I note that Billmac doesn't say that it was an actual E. f. 'Green and Gold', so it could be japonicus. Euonymus will occasionally grow from damaged roots, so it might be a belated sprout from that bush, or maybe from the neighbor's--if they have one!