The plaque commemorates Sir James Drake - the mastermind behind the construction of Britain's first ever motorway, the Preston By-Pass, now part of the M6, which opened 50 years ago today.
It was a chilly morning, but only warm comments were made about Sir Drake, the ex-County Surveyor and Bridgemaster for Lancashire.
Minister of State for Transport, Lord Andrew Adonis and Chairman of Lancashire County Council, Cllr. Alan Whittaker headed the event and both gave a few words before unveiling the plaque.
Alan Whittaker passionately addressed the crowd. He said: "We are proud to be the forerunner of such a economic influence".
He went on to quote Harold MacMillan's words when he opened the Preston By-Pass in 1958. He said: "In the words of the then prime minister Harold MacMillan; "what Lancashire does today, the rest of the country does tomorrow."
Lord Adonis described how the Preston By-Pass had no speed limit, no crash barriers and no hard shoulders when it first opened 5th December 1958. He described the Preston By-pass as a "transport revolution and also a social revolution".
86 year old Harry Yeadon from Lytham St. Anne's who helped construct the by-pass and eventually replaced Sir Drake as County surveyor and Bridgemaster was at the event - as well Sir James Drake's two daughters.

(Left: Sir Drakes two daughters admire the plaque in honour of their father)
Also at the unveiling of the plaque today was Anne Williams, 62, from Bamber Bridge who was 12 years old when she attended the opening of Preston By-Pass 5th December 1958.
She recalled how the day was and what it was like meeting Prime Minister Harold MacMillan.
She said: "The weather now is exactly the same as on the day that it happened 50 years ago. I was 12 years old and 60 pupils had been chosen from Walton-Le-Dale secondary modern."
"Harold MacMillan walked along the school children. I was very small and standing at the front, with bright red hair. He came along and tapped me on the head and said "Hello Ginger, this is a very important day for you and one you'll never forget." and I'm happy to say I havn't forgotten it."
"After I'd spoken to Harold MacMillan I always thought that maybe he'd inspired my career for the future because I then became a lorry driver. I was a lorry driver for 30 years and i've always travelled the M6 and all the other network of roads."

The "Cumberland Gap"
Today's 50th anniversary celebration coincided with the opening of the M6 upgrade between Carlisle to Guards Mill. What was nicknamed the "Cumberland Gap" has now been filled, enabling drivers to travel from London all the way to Glasgow on the M6. The 5 1/4 miles stretch of road cost £117 million; 55 times more than the 8 1/4 miles Preston By-Pass which cost £3 million in 1958.
Bob Baldwin, Performance manager for the motorway network in Lancashire and Cumbria expressed his delight for both of today's celebrations.
He said: "I think today is fantastic and it's very important. Who would believe jut 50 years ago what an impact the motorway network would have on our country."
"We are celebrating today 50 years of the motorway achievement but we should also add today is also the opening of the final section of the M6 which is the upgrade between Carlisle and Guards Mill. Some people might think it's taken my government 50 years to build the rest of the M6 motorway but that being said we're looking at the final section of the motorway today which is being opened by Lord Adonis and now we have a motorway that goes all the way up to Scotland on the West Coast."
He went on to talk about the sentiment of celebrating the two events today. He said: "It was very important that we did this. The government sought to ensure that the upgrade was opened today on the 50th anniversary of the M6 Preston By-Pass. That was our target and thankfully we achieved that target."
Picture courtesy of The Motorway Archive - http://picasaweb.google.co.uk/pghewitt1/PrestonByPassImages#5257491096549449138 - Sir James Drake
Other pictures courtesy of Alan Whittaker's photographer Denis Oates.