This Yemeni recently split the earliest J-M205 paraclade J-Y64012.
First he just submitted his VCF, which YFull now accepts, given the FTDNA $99 BAM file download fee. The TMRCA estimate based on the VCF, however didn't make sense. It was 1250 ybp.
I recommended this man to submit the BAM. Now that he did, we have a figure of 2300 ybp. Based on this date, and the overall context of J-M205 (ancient and modern), the simplest explanation is that this migration to France / England was Roman-mediated.
The Yemeni is relatively speaking, a remnant. I do not know more about his specific lineage's ancestry or when they may have migrated to Yemen. Because J-M205 is spread throughout the Levant, Mesopotamia and Arabia, I have held off from theorizing on a more specific origin. When I say this Yemeni is a remnant, I mean that his ancestors most likely have been living in the Middle East since at least 3700 BC, when the most recent common ancestor of all J-M205 lived.
I was just contacted by a researcher who knows the sample:
"The sample owner said that his ancestors came from the Levant, mostly from Palestine, as soldiers in the Ottoman army, and after that they settled in Yemen. This is what he knows about the history of his family."
Exogenous J-M205 Found in Roman-Era York
We have seen this Roman-mediated migration pattern already in an ancient sample of J-M205, 3DRIF. He was found in Roman-era York without his head. He had Middle Eastern autosomal DNA.
The moral of the story - submit your BAM file to YFull for the most accurate age estimation.
Do not test Big Y if you don't want to pay the $99 BAM download fee.
For more information on J-M205: