* Earlier this week the pound rose to a six-week high
* Pound unmoved by Scottish court ruling on parliamentsuspension
* Graphic: World FX rates in 2019 http://tmsnrt.rs/2egbfVh
* Graphic: Trade-weighted sterling since Brexit vote http://tmsnrt.rs/2hwV9Hv(Updates throughout, quote)
By Olga Cotaga
LONDON, Sept 12 (Reuters) - Sterling slipped a quarter of apercent on Thursday against the euro but firmed against thedollar, as the single currency enjoyed a broad rebound in thewake of the European Central Bank's new stimulus announcement.
The ECB cut its deposit rate by 10 basis points andannounced a bond purchase programme of 20 billion euros a month,starting from November, but the move failed to live up to somedovish market expectations, leading to some volatile euro moves.
The single currency had initially fallen after the ECBstatement and touched a 2-1/2 month low against the poundat 88.86 pence.
It then rebounded across the board as ECB President MarioDraghi hinted at the limits of monetary policy and called ongovernments to expand budget spending.
By 1545 GMT the euro was half a percent higher versus thedollar and also rose 0.3% to the pound at 89.61 pence.
Against the dollar, sterling firmed 0.2% at $1.2351, close to $1.2385, a high it surged to on Monday whenno-deal Brexit worries receded and some economic data came inbetter than expected.
The euro volatility came on a day of calm for sterling onthe Brexit news front as investors weigh up Britain's chances ofsecuring a divorce deal with the European Union ahead of itsscheduled departure from the bloc on Oct. 31.
With parliament suspended for five weeks by Prime MinisterBoris Johnson -- a move judged unlawful by Scotland's highestcourt of appeal on Wednesday -- traders lacked new Brexitdevelopments to digest and stayed on the sidelines.
"For now, avoiding a no-deal Brexit by Oct. 31 is the onlysilver lining for the pound," London and Capital Group toldclients.
The court ruling has prompted calls for lawmakers to returnto work as the government and parliament battle over the futureof Brexit. Britain's Supreme Court is set make a ruling nextweek.
Outcomes ranging from leaving without a deal to anotherreferendum that could cancel the whole process are forcing someinvestors to stay away from the currency.
Instead they are trading implied volatility via optionsmarkets -- two-month volatility, which stretches beyond thecurrent Oct. 31 Brexit deadline, has come off three-year highsto around 9.40 vols. That is down from 15.45 vols on Sept. 3,the highest levels since the 2016 referendum.
Sterling's steadiness was also partly due to the amount ofshort positions hedge funds held on sterling, analysts said. Inthe week to Sept. 3 leveraged funds reduced their positionsslightly, but the amount of contracts, at $6.42 billion, wasclose to the highest since April 2017.(Reporting by Olga Cotaga and Sujata Rao; Editing by HughLawson and Catherine Evans)