dear Downtoearthdigs, thank you for answering my question though I must say your answer is rather depressing. Jonathan
This is called Field Horsetail.
The organic method of control is digging the rhizomes as deeply as possible and as regularly as you can. This can take years and it may not be possible to eradicate the weeds completely.
You can apply a chemical herbicide with glyphosate in the summer. Stepping on the plants to bend and bruise them prior to spraying can help with chemical intake into the plants.