* FTSE 100 rises 1 pct, touches highest since Sept 2014
* Index rallies after new ECB policy
* UK stocks underperform peripheral Europe
* Royal Mail gains after update (Updates with closing prices)
By Alistair Smout
LONDON, Jan 22 (Reuters) - Britain's top share index touched a four-month high on Thursday after the European Central Bank launched a substantial sovereign bond purchase programme to fight deflation and spur growth.
The ECB said its new quantitative easing programme and existing asset purchase schemes will pump 60 billion euros ($69 billion) a month into the euro zone economy from March until September 2016.
The move boosted appetite for shares across Europe and Britain's FTSE 100 touched a peak of 6,808.18 points, its highest since Sept. 22.
"The higher-than-expected monthly amount to be purchased is compensated (for) by the time limit on the programme," said François Savary, chief strategist and head of asset services at Swiss Bank and fund management group Reyl & Cie.
He described it as a "great compromise", adding: "At the end of the day, Mr Draghi and the supporters of the QE policy move must be quite satisfied".
Britain's FTSE 100 closed 68.59 points higher, up 1 percent, at 6,796.63, rising for a sixth straight session.
However, the index underperformed peripheral euro zone markets that stand to benefit from QE, with Spanish and Italian indexes up 1.7 percent and 2.4 percent respectively.
The FTSE 100 "is only an indirect beneficiary of this policy," CMC Markets analyst Jasper Lawler said.
Expectations the ECB would start printing money have fuelled recent gains, with the FTSE 3.8 percent higher this week.
While investors welcomed the move, some were sceptical about how quickly its effects would be felt.
"The bare outlines are broadly in line with what the speculation has been over the last couple of days," said Andrew Milligan, head of global strategy at Standard Life Investments.
"But on what terms will we see a sustained adjustment in the path of inflation? We have to see a response in the real economy."
Among individual movers, Royal Mail rose 3.6 percent after saying group revenue for the nine months to Dec. 28 rose 1 percent, a slowdown from the half year as an improved parcels performance was offset by lower letter volumes.
British insurer RSA rose 3.3 percent to 466 pence after Credit Suisse raised its stance to "outperform" from "neutral" and pushed its target price to 525 pence from 450. ($1 = 0.8752 euros) (Editing by Catherine Evans/Ruth Pitchford)