Wasp/Bee/Hoverfly?

Observation - Wasp/Bee/Hoverfly?. Description: Sorry, no photo. A bee or (more probably) wasp or hoverfly on bramble then hedge parsley (torilis japonica) in the garden (a 'wild' garden!) The really significant identifier was that the underside of the abdomen was a solid yellow - no kinds of stripes

Sorry, no photo.
A bee or (more probably) wasp or hoverfly on bramble then hedge parsley (torilis japonica) in the garden (a 'wild' garden!)
The really significant identifier was that the underside of the abdomen was a solid yellow - no kinds of stripes.
It kept raising the (rather pointed) end of the abdomen, involving bending the abdomen slightly backwards, as if to display the colour.
Sorry I can't give better details but the yellow was so startling I hardly noticed the rest!
I don't remember the wings being open (a la hoverfly) when at rest - but wouldn't guarantee.
Any ideas?