my understanding is most of the mail got shipped down to spain, from there it flys to the USA
that was what cnn had on this AM
from royalmail
Closed airspace - impact on International mail services
International mail due to leave or enter the UK is currently affected by the closure of the UK airspace, as a result of the Icelandic volcano. Because no mail is entering or leaving the UK by air at present, delays to international mail are therefore inevitable.
We have robust contingency plans in place that mean mail leaving the UK for all European destinations is being transferred to road and sea services.
Contingency plans also include the shipment of items to the USA by sea, the first of which is expected to arrive in the USA around the 30th April. We are exploring all options possible for alternative routes to destinations in the rest of the world, for as long as the situation continues. In the meantime, this mail is being stored in order for it to continue its journey as soon as alternative routes become available or flights resume.
Many European postal authorities are also using alternative transport solutions to move international mail; customers should check with the relevant foreign postal authorities for further details.
We are sorry we cannot currently estimate how long international mail will be affected by this unavoidable event, but we are continuing to deploy and review contingency plans, to keep as much of our customers' mail moving as possible.