Not literally as the Channel was dry land at the time. At www.nerc.ac.uk/press/releases/2013/81-neanderthals.asp … the St Brelade cave in Jersey contains sediments dating back to the last Ice Age, a useful resource. It has produced more Neanderthal tools than all of the mainland UK sites put together. Using Luminescence Dating methodology on sand grains in the sediments, a rather clever technique, the sediments have been dated between 100,000 and 47,000 years ago. This suggests Neanderthal teeth found in the same sediments in 1910 are much younger than previously believed – or calculated (or even dated). This raises a query – what methodology was used to date them, if any. Was it assumed they were later, on the basis of human development chronology – and how much does this human development chronology owe to the idea it takes a lot of time for organisms to develop incrementally, stage by stage, and very slowly? Is this another consensus theory based more on assumption than fact?
See also Jersey Heritage for more details