TUPE (Transfer of Undertaking Protection of Employment) will most certainly apply. Nestle in line with the law will have to offer ongoing employment on existing terms and conditions to those employees who can or wish to move.
The sticking points in these scenarios come when there is no re-location package offered, as there is no legal requirement to do so. Partners may be in other work, children may be settled in schools etc.
Some will be able to go easily others will not...Other pitfalls like trying to sell your house and buy another within a tight timescale will also apply. Whilst these regulations places an onus on employers to consider carefully plans to move (by giving the employees the right to enduring employment) practicality means few ever take it up.
TUPE rules were last altered in 2007, we all know which colour government was in power at that time and whilst sections of the act were strengthened business lobbying Government meant no provision was placed within the legislation to facilitate compulsory assistance in re-location expenses.
If a firm wants to move it's management structure it will offer all sorts of incentives to allow that as is proven. If the chaps on the warehouse floor want to move then they pretty much have to fend (and pay for the move) themselves.
Yet another example of where the Government of the day looked to improve the working man's lot but were got at by big business. No doubt a few ex Labour ministers are enjoying a directorship or two off the back of this.
This essentially has become a big problem particularly for parts of London, many firms are looking to re-locate outside of the capital where wage bills are much lower. The single market and opening of the borders to the Eastern Bloc means a ready supply of labour is available to work at much lower rates and no doubt this is a major factor in Nestle's move.
http://www.idea.gov.uk/idk/core/page.do?pageId=6908271