This raises several interesting issues.

]Draft horses could already have been popular in the more easily tillible English country side as opposed to the relatively virgin fields in the US that require oxen to break.

I belived so - you see few references to oxen being used this way in England and plenty (including in Mansfield Park) to horses. Also there is a great deal of heavy horse "culture" still existing in Britain with the main breeds still being preserved in places like the hop museum in Kent, for use as dray horses for breweries etc.

However, in North East Scotland there used to be a secret society, a kind of early trade union called "the Horseman's Word." According another part of the site linked below the Up to the 18th cent. "the main source of traction on the farm was the ox." This may be specific to that part of Scotland or it may simply be that the change from oxen to horses was so long ago that the residual culture pertains to the horses - that concerning oxen having long gone.

] As you say I think there would be seasonal workers that followed the harvest North to South the way they do now for fruit crops.

There seem to be few refererences. You hear of gypsies working seasonaly but I get the (entirely subjective) idea that in the England of the time it was more a matter of all the locals pitching in, women and children too (the school year in Britain is still patterned in order to allow the children to help with the harvest, with a long break in late summer).

] Since sheep shearing gangs would come through in the spring making good wages would these be the same men available in the fall for harvest

My impression is that whilst labour was always short at harvest time, and that travelling people such as gypsies could always make money at harvest time, there was not the sort of mass movement of itinerent labourers that you saw following the grape harvest in France until recently or that you can still see moving from Coffee to Cotton picking in places like Nicaragua. Again this is subjective but I would think that any mass movement of labourers through the season would leave more of a mark on the cultural landscape.

What we have had in living memory is the hop harvest in Kent where thousands of East Enders from London would go and pick hops as a working holiday. Something that I came across in the course of researching the MT was that there used to be a substantial hop industry in Hampshire which declined in the nineteenth century. Where the labour came from for that I do not know however, nor wether the fact that it was easier for the Kentish hopfields to get labour from London was a factor in its demise.

It also occurs to me to wonder about the vagrants and rural poor that were usually seen as such a menace. Did they become a valuable source of extra labour during havest, only to become pariahs again once it was safely gathered in? It seems to me that a situation where so much labour was needed during a short, specific time, was bound to have all sorts of effects on the pattern of rural life and society.