The chancellor used the spring statement on Wednesday to say he had accumulated as much as £26.6bn of additional spending power from stronger tax receipts - on the forecasts of the government's independent economics forecaster, the Office for Budget Responsibility (OBR) - which could be used to boost public services if Brexit passed smoothly.
The downgrade was included in an otherwise upbeat set of forecasts from the economic watchdog in yesterday's spring statement.
Mr Hammond warned that Tuesday's Commons defeat for Theresa May's Brexit plan "leaves a cloud of uncertainty" hanging over the British economy.
The chancellor has announced he will launch a "full three-year Spending Review" before the summer break as long as Brexit is agreed and the "uncertainty lifted" in the next few weeks.
Chancellor of the Exchequer Philip Hammond (picture) issued a fresh warning that leaving the European Union (EU) without a deal would damage the United Kingdom economy and leave people less well off.
Growth forecasts in 2020 and 2021 stood at 1.4 and 1.6 percent respectively, compared with forecasts of 1.4 percent for both years made in October.
He added: "I need to be straight with the House: a no-deal Brexit would deliver a significant short- to medium-term reduction in the productive capacity of the British economy".
"Higher unemployment; lower wages; higher prices in the shops".
New half-yearly fiscal forecasts showed that Britain's public finances, at least in the short term, were in better shape than in October, when Philip Hammond gave an annual budget statement, despite a weaker outlook for the country's economy.
Analysts expect parliament instead to favor delaying Britain's departure beyond the March 29 exit date, in a further vote due Thursday.
He said that it was "disappointing" that the chancellor had missed the opportunity to provide desperately-needed funding for local services, and added that Brexit can not be a distraction from the challenges facing our public services.
Britain's leading tax and spending thinktank said the chancellor's fiscal headroom - described by Hammond as a "deal dividend" - could be effectively wiped out under a no-deal Brexit.
However, Britain's independent budget forecasters said nearly half of Hammond's fiscal headroom might be lost, depending on how official statisticians treat student loans in the public accounts.
Earlier yesterday, the government unveiled plans for temporary tariffs if the United Kingdom crashes out without a deal.
Bryce Harper hit by pitch, limps off field
After the game, Phillies manager Gabe Kapler said Harper suffered a right foot contusion and perliminary x-rays were negative. Harper was hit in the ankle on a 2-0 pitch by Blue Jays pitcher Trent Thornton in the bottom of the sixth inning.