Does the Irish consignee need a British EORI number?

No. On the landbridge Union goods cross Great Britain under transit, so there is no import and no importer in GB. The EORI and the guarantee must be held by the holder of the transit procedure, usually the forwarder's customs agency. The Irish consignee only accounts for an intra-Community acquisition of the goods in Ireland.

Does DDP Dublin mean the seller pays duty in Great Britain?

No, because there is no duty to pay in Great Britain: the goods cross GB under transit and the supply from Poland to Ireland is intra-EU. DDP and DAP divide freight, risk and costs between the parties, but they do not create an import obligation where there is no import. A "UK importer" clause in a landbridge contract is a mistake.

What happens if the transit is not closed in Ireland?

Customs may recover duty and VAT from the holder of the procedure out of its guarantee, as if the goods had been placed on the market without clearance. That is why OTSL checks in the system after delivery that the office of destination has confirmed the end of the procedure, and only then treats the order as closed on the customs side too.

Landbridge is transit, not import

Union goods from Poland travelling to Ireland through Great Britain are not imported into GB. They move under a transit procedure and customs supervision, with charges suspended until the transit is closed in Ireland. The supply from Poland to Ireland itself is intra-EU: no duty, no import VAT, and VAT follows the rules for intra-Community supply and acquisition. Incoterms divide cost and risk between seller and buyer, but on the landbridge they create no import obligation in GB. A common mistake is to look for the "UK importer", who does not exist in this movement.

Why is crossing Great Britain not an import?

An import is the entry of goods into a customs territory with the intention of leaving them there: an import declaration, duty and VAT. Transit is something else. The goods enter the United Kingdom solely to cross it, and the GB customs authority agrees to that on condition that the goods remain under supervision and leave the country within the set time. Duties are not collected but secured by a guarantee, and they cease to be an issue the moment the office of destination in Ireland confirms that the procedure has ended.

The United Kingdom is a member of the common transit procedure, so Union goods cross it on one T2 declaration from the office of departure in the EU to the office of destination in Ireland. For the British system those goods are "in transit", not "on the market". That is why there is no British import declaration, no British import VAT and nobody to enter as the importer in the UK.

Who is responsible for the goods and the charges under transit?

Transit has a holder of the procedure (formerly the "principal"): an operator with an EORI number who lodges the T2 declaration, provides the guarantee and is answerable to customs for the goods reaching the office of destination intact. That is usually the forwarder's customs agency, not the consignee. The Irish consignee needs no British EORI, files nothing in GB and pays no charges there.

The risk lies elsewhere. If the transit is not closed in Ireland, because the goods were not presented at the office of destination or went missing on the way, customs may recover the charges from the holder of the procedure out of its guarantee. That is why the customs agency follows up the closure after delivery: a missing confirmation is not a formality but an open claim for duty and VAT on goods that in reality reached Dublin.

The landbridge without import step by step

Check the status of the goods. Union goods (produced in the EU or released for free circulation in the EU) travel on a T2; non-Union goods coming from a third country travel on a T1. The status decides the type of transit, not the direction of travel.
Agree Incoterms without a "UK importer". DAP Dublin or DDP Dublin settle who pays the freight and bears the risk; neither creates an import obligation in GB, because there is no import in GB.
Name the holder of the procedure. The OTSL customs agency, with its EORI and guarantee, opens the T2 transit at the office of departure; an MRN is issued.
Prepare the GMR and the PBN. OTSL creates the GMR in GVMS with the transit MRN for entry into GB and the PBN in the Revenue service before the ferry to Ireland; both within the order.
Deliver and present the goods. The goods go to the office of destination or to an authorised consignee in Ireland; the consignee acknowledges receipt on the CMR (the Convention on the contract for international carriage of goods by road).
Confirm closure of the transit. OTSL checks in the system that the procedure has ended and the guarantee has been released; only then is the order closed on the customs side as well.

Definitions

Transit: a customs procedure allowing goods to be moved through a customs territory without charges being collected, under supervision and against a guarantee.
T2 and T1: T2 is transit of Union goods (through a third country they keep their Union status); T1 is transit of non-Union goods. The United Kingdom is a member of the common transit procedure.
Holder of the procedure: the party lodging the transit declaration and responsible for its closure; formerly the "principal".
EORI (Economic Operators Registration and Identification): the trader identification number in customs matters; needed by the holder of the procedure, not by the Irish consignee of Union goods.
MRN (Movement Reference Number): the number of the transit declaration, entered in the GMR and the PBN.
GMR (Goods Movement Reference): the reference in the British GVMS (Goods Vehicle Movement Service) for a laden vehicle to enter GB.
PBN (Pre-Boarding Notification): the notification in the Irish Revenue service before a ferry from GB to Ireland, gathering the MRNs for the goods on the vehicle.

Checklist: is there really no import in this order?

The goods have Union status and travel on a T2, not a T1.
The consignee is in the Republic of Ireland, not in Northern Ireland or England (postcode, currency, VAT).
The contract contains no clause about "UK import clearance" or a British importer.
The holder of the procedure (customs agency) has an EORI and a guarantee covering the charges.
GMR and PBN prepared with the MRN of the same transit.
It is agreed who confirms closure of the transit and by when.

When does an import into Great Britain arise after all?

The rule "landbridge is transit, not import" covers goods that merely cross GB. It does not apply where goods stay in Great Britain, even in part: one pallet unloaded in England, a transfer to another vehicle outside the procedure, or a sale en route to a British buyer. For that part an import into GB arises, with a declaration and an importer, while the rest continues under transit. An import also arises when the transit is interrupted without customs consent or is never closed. Whether the consignee in Ireland pays anything therefore depends on a correctly executed transit, not on the Incoterms clause.

The OTSL role

The OTSL customs agency acts as holder of the procedure: it opens the T2 transit, provides the guarantee, creates the GMR and PBN and follows up closure after delivery as part of its customs clearance service. Which type of transit applies when is explained in T1 or T2 transit, and who really pays duty and VAT under different trade terms in Incoterms mismatch: DAP versus DDP. The lane overview is on the transport to Ireland page.