One key obstacle, access to a train maintenance and storage facility, looks to have been overcome following a decision by the Office of Rail and Road (ORR).
The regulator said Eurostar’s London depot would be able “if required” to accommodate additional trains, following receipt of an independent report it commissioned.
The report follows growing interest in providing extra services between St Pancras and continental Europe, with Virgin Trains, Spanish start-up Evolyn and a UK brand, Gemini Trains, keen to enter the market.
Access to a suitable depot close to London for maintenance and storage is a critical requirement for more operators to begin services.
The ORR added changes to the depot’s operational and maintenance arrangements, plus possible alterations to infrastructure, would be required to access extra capacity and allow more trains to be stabled and maintained there.
Final conclusions will follow a further consultation period this month, in which Eurostar is expected to object to sharing its facility. Eurostar has had a monopoly on services since the Channel Tunnel opened in 1994 and competitors want to challenge it on routes to Paris and Brussels and to add destinations including Amsterdam.
A Virgin Group spokesperson said: "Finally a green signal for competition. The Temple Mills depot is the only facility in the UK which can accommodate European-style trains and claims suggesting it was at capacity have been blocking Virgin from coming to the line.
"Virgin is therefore very pleased with the outcome and we thank the ORR for commissioning this report, which will now unlock competition on the cross-Channel route for the benefit of all passengers.
“There are no more major hurdles to overcome, and Virgin is ready to take up the challenge, given its award-winning experience in the train industry and track-record for building globally successful travel brands. We expect to be able to make an announcement very soon. Watch this space."