Question: How many copies were sold of the last UK number-one single that was written by Noddy Holder and Jim Lea?

Context paragraphs:
You Boyz Make Big Noize (song): You Boyz Make Big Noize is a song by the British rock band Slade, released in 1987 as a non-album single.  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Lea.  Named after the band's 1987 album of the same name, the song reached No. 94 in the UK, remaining in the chart for the one week.

We Won't Give In: "We Won't Give In" is a song by the British rock band Slade, released in 1987 as the fourth and final single from their fourteenth studio album "You Boyz Make Big Noize".  The song was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Lea.  It failed to reach the UK Top 100, reaching No. 121.

We'll Bring the House Down (song): "We'll Bring The House Down" is a song by the British rock band Slade, released in 1981 as the lead single from their ninth studio album "We'll Bring the House Down".  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Slade.  The band's first single to reach the UK Top 40 since 1977, the song peaked at No. 10 in the UK, remaining in the chart for nine weeks.

My Friend Stan: "My Friend Stan" (stylised as "MY FRIEИD STAИ") is a song by the British rock band Slade, released in 1973 as the first single from the band's fourth studio album "Old New Borrowed and Blue".  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Chas Chandler.  It reached No. 2 in the UK, spending eight weeks on the chart.  The single was certified UK Silver by BPI in October 1973.

(And Now the Waltz) C'est La Vie: "(And Now the Waltz) C'est La Vie" is a song by the British rock band Slade, released in 1982 as the lead single from the band's eleventh studio album "The Amazing Kamikaze Syndrome".  It was also included on its 1984 American counterpart "Keep Your Hands Off My Power Supply".  The song was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Lea.  It reached No. 50 in the UK, remaining in the charts for seven weeks.

Everyday (Slade song): "Everyday" is a song by the British rock band Slade, released in 1974 as the second single from the band's fourth studio album "Old New Borrowed and Blue".  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Chas Chandler.  It reached No. 2 in the UK, spending seven weeks on the chart.  The single was certified UK Silver by BPI in April 1974, only three days after its release.

Merry Xmas Everybody: "Merry Xmas Everybody" is a song by the British rock band Slade, released as a non-album single in 1973.  The song was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Chas Chandler.  It was the band's sixth and final number-one single in the UK.  Earning the UK Christmas Number One slot in December 1973, the song beat another Christmas-themed song, Wizzard's "I Wish It Could Be Christmas Everyday", which reached fourth place.  It remained in the charts for nine weeks until February 1974.

Slade: Slade are an English glam rock band from Wolverhampton.  They rose to prominence during the early 1970s with 17 consecutive top 20 hits and six number ones on the UK Singles Chart.  The "British Hit Singles & Albums" names them as the most successful British group of the 1970s based on sales of singles.  They were the first act to have three singles enter the charts at number one; all six of the band's chart-toppers were penned by Noddy Holder and Jim Lea.  As of 2006, total UK sales stand at 6,520,171, and their best-selling single, "Merry Xmas Everybody", has sold in excess of one million copies.

Take Me Bak 'Ome: "Take Me Bak 'Ome" is a song by the British rock band Slade, released in 1972 as a non-album single.  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Chas Chandler.  It reached No. 1 in the UK, giving the band their second number one single, and remained in the charts for thirteen weeks.  The song was certified UK Silver by BPI in 1972.  In the United States, the song reached No. 97.  The song would be included on the band's 1973 compilation album "Sladest".

Skweeze Me, Pleeze Me: "Skweeze Me, Pleeze Me" is a song by the British rock band Slade, released in 1973 as a non-album single.  It was written by lead vocalist Noddy Holder and bassist Jim Lea, and produced by Chas Chandler.  It reached No. 1 in the UK, giving the band their fifth number one single, and remained in the charts for ten weeks.  The song was certified UK Silver by BPI in July 1973.  The song would be included on the band's 1973 compilation album "Sladest".

Supporting paragraphs: Slade Merry Xmas Everybody
Answer: in excess of one million copies