CHANNEL TUNNEL Rail Link client Union Railways was this week reviewing its options after failing for a second time to win permission to work 24 hours a day at King's Cross St Pancras.
The decision is likely to have a major impact on the construction programme for section two of the link, which is due to open in 2007.
Union Railways needed the extra time so vital work could be completed before a major possession on the Thameslink line which runs through the site.
This 25 1/2 week possession is scheduled to start in September.
The cost of extending this is estimated to be about £50M plus £1M a week in compensation payments for train operators.
Union Railways had appealed against Camden council's refusal to allow longer working hours in December 2003.
'Extending the construction programme and missing key targets would obviously be very costly and disruptive but this does not mean that the construction programme is sacrosanct, ' said planning inspector Graham Self.
'After all, the programme has been delayed before so that graves could be treated sensitively and it seems to me that the needs of the living are at least as great as the needs of the dead.
'In terms of human rights, I find that it is not proportionate for residents living next to the site to bear the burden which would be placed on them if the proposed arrangements were approved, ' he said.
Camden council said that had Union Railways offered a better package of mitigation measures for residents, it might not have objected to the extension.
Union Railways said extended hours were needed because of delays caused by unforeseen problems, including late running utility diversions and the discovery of several thousand old graves in the St Pancras cemetery.