GLOBAL markets have scaled record heights as investors cheered US President Donald Trump's pledge to slash taxes and unleash an infrastructure spending spree.

More than £30 billion was added to the value of Britain's blue chip companies as the FTSE 100 Index soared 119.46 points to a record all-time closing high of 7,382.9.

Across the Atlantic, the Dow Jones Industrial Average was also soaring, as the US President's warmly-received speech to Congress inspired the index rise above the 21,000 points mark for the first time in its history.

Mr Trump struck a less confrontational tone during his speech on Tuesday, vowing to reform taxes, slash red tape and ramp up spending on defence and infrastructure projects.

It comes after the London market embarked on a remarkable winning streak at the beginning of the year - notching up 12 record closes on the bounce - as investors cheered Mr Trump's economic policies.

On the second tier, the FTSE 250 Index also secured an all-time closing high on Wednesday, jumping 212.3 points to 18,983.01.

In Europe, the Cac 40 in France and Germany's Dax raced ahead, climbing 2.1 per cent and 1.97 per cent respectively.

As the London market closed, the Dow Jones and the S&P 500 were up 1.42 per cent, while the Nasdaq Composite was 1.3 per cent higher.

Jasper Lawler, senior market analyst at London Capital Group, said stocks in line to benefit from Mr Trump's proposed spending splurge were pushing the markets higher.

"A more inclusive speech from the US President has seen global stocks surge, taking the Dow Jones above 21,000 for the first time.

"There has been a lot of criticism for the lack of detail on how Trump plans to deliver his 'don't tax and spend' reforms. That misses the point of the speech.

"By bringing Congress on side, Trump's plans to 'restart the engine' of the US are a lot more likely to become policy."

The FTSE 100 Index was also enjoying an uplift from the collapse in the pound, which took a substantial hit after the US dollar strengthened on market speculation that the US Federal Reserve could hike interest rates at its meeting on March 15.

Sterling's slump since the Brexit vote has proved beneficial for multinational companies listed on the London market as many tend to benefit from earnings in currencies, such as the US dollar, which are performing better than the pound.

The UK currency deepened its losses on Wednesday after sliding back in morning trading when a fresh tranche of UK manufacturing data showed an unexpected slip in February.

The pound was down 0.4 per cent versus the US dollar at 1.232 and 0.3 per cent lower against the euro at 1.165.

The price of oil was marginally ahead at $56.43 a barrel after paring gains in response to record high crude inventories in America.

In UK stocks, Irish construction firm CRH and equipment rental company Ashtead were the biggest risers amid hopes that their US businesses will receive a boost from President Trump's policies.

Ashtead group jumped more than five per cent, or 95p to 1,751p, while CRH climbed 134p to 2,854p.

Broadcaster ITV surged 9.2p to 211.7p as pre-tax profits held up despite a Brexit-induced drop in full-year advertising revenues.

The group, home to shows such as The X Factor and Broadchurch, said net advertising revenues dropped three per cent to £1.67 billion amid ''political and economic uncertainty'' and cautioned it expects declines of around six per cent in the first four months of 2017.

Royal Mail was the biggest faller on the London market, dropping 7.6p to 407p, after Ofcom said it would not make sweeping changes to the way it operates, but would retain its 2012 framework until 2022.

Ofcom said safeguards already in place, such as a cap on second class stamp prices to protect vulnerable consumers, are generally ''working well for people and businesses who use the post''.

The biggest risers on the FTSE 100 Index were Ashtead up 95p to 1,751p, CRH up 134p to 2,854p, Glencore up 15.7p to 337.75p, Next up 176p to 4,003p.

The biggest fallers on the FTSE 100 Index were Royal Mail down 7.6p to 407p, Babcock International down 11.5p to 936.5p, Randgold Resources down 85p to 7,425p, Centrica down 2.4p to 224.5p.