Today's main event is due at 09.30 GMT 24 Jan

No early clues with GBPUSD steady around 1.2480 and EURGBP 0.8608 after reversals from 1.2548 to 1.2463 and 0.8582 to 0.8617

Is the risk to the upside for GBP pairs or has that already been factored in as I discussed in my preview yesterday which I reproduce here below now in case you haven't seen it. A ruling in the govt's favour will see the pound on the back foot but in essence Article 50 is going ahead regardless of which way the cookie crumbles.

"The time to set your alarm clocks for is 09.30 GMT when the judgement from December's meeting will be given with a summary lasting around 5 minutes. Both will be published on the Court's website and be broadcast live from there too.

The issue is :"Does the Government have power to give notice pursuant to Article 50 of the Treaty on European Union of the United Kingdom's intention to withdraw from the European Union, without an Act of Parliament providing prior authorisation to do so?"

Don't confuse this verdict with anything UK PM May said last week giving a vote to both Houses of Parliament. That vote is for the final negotiated deal to include trade, immigration et al while tomorrow's verdict rules on whether the UK govt can trigger Article 50 without first getting approval from parliament, and it's an appeal by the govt against a November High Court decision.

In December MPs approved a motion in the Lower House (Commons) to stick with triggering Article 50 by the end of March with a caveat that govt should reveal its Brexit plans in advance. However, again, this does not oust the need for the case, with lawyers for the government in the Supreme Court hearing calling the motion "significant", but conceding it was not legally "binding".

It was reported over the weekend that Brexit secretary David Davis has a short Article 50 Bill lined up ready in case the govt lose its appeal but his Brexit department declined to confirm or deny.

If the Supreme Court rule against the govt it won't be a major surprise imho and one that might already beconceded by some govt ministers but should give the pound a boost if only knee-jerk. Article 50 will still be expected to be triggered, and probably by the end of March still but the verdict might just add some uncertainty, and in this case that might be GBP-positive.

This case isn't the only game in town for the govt to consider as another one regarding Article 127 which refers to whether leaving the EU also means leaving the single market is scheduled to be heard in early-Feb."