The artist is Groves. The painting is a young man dressed in red plaid holding a golf club.

Okay, you have an authentication number but who\authenticated it, and what exactly is your question?

There is a tag on the back of the picture that says "Handpainted assurance of quality, Reg. No 6020685. My question is, can anyone tell me anything about the painting and the artist. Any history?

The name Groves doesn't come up at all as an artist of any renown. Your description of the painting doesn't mean a lot. Even if you posted a pic of your find, I doubt whether you find out any new information. You could take it to an art gallery and see if they know anything about this artist.

No well known artist with put anything on his/her material stating a numbeer and comments as in 'handpainted assurance of quality'.

Tick