As Pettigrew walked towards me with that distinctive gait outside a McDonald's franchise yesterday, I was transported back to the 1970s, when it rained goals at Fir Park.
On a weekend when Motherwell visit Celtic Park, one of the Lanarkshire club's greatest ever strikers took me back to his halcyon days. Celtic were Pettigrew's victims more than once, but most notably amid an epic January 1975 mudbath in Glasgow. Back then, he was a Scotsport icon, Arthur Montford going doolally as the striker struck again and again. Eager and wiry, Pettigrew was relentless. In one of his hot periods at Fir Park, between 1975 and the end of 1977, he scored 82 goals in two-and-a-half seasons.
"Goals were my thing," Pettigrew says. "From the moment I stepped on to the park it was all I wanted to do. I had pace and I also had attitude. If I hadn't scored by the 90th minute I'd still be looking to get one. I came to understand later in my career that there was more to being striker than goals but, for the most part, that was all I focused on."
In a career spanning Motherwell, Dundee United, Hearts, Morton and Hamilton Academical, he fell out with many, including Willie McLean, Ally MacLeod, Jim McLean and Wallace Mercer. "I couldn't keep my mouth shut," says Pettigrew. "The main reason being, I wouldn't take sh**e off anyone."
Pettigrew burst on to the scene in 1975, scoring a barrowload in a Christmas trouncing of Ayr United and finally persuading manager Willie McLean to start him against Celtic the following month. On a rain-sodden pitch, and wearing Motherwell's famous claret sash of the time, Pettigrew and Bobby Graham gave Kenny Dalglish and co a jolt in their 3-2 win. You can watch it again on YouTube; it is a Scottish game steeped in mud and skill.
"My career took off after that," says Pettigrew. "I grew in confidence and scored countless goals. They seemed to come in batches: seven in eight games, 14 in 10 games, stuff like that. I remember that  game very well against Celtic. It was absolutely pishing it down. Bobby Graham got one, I got two, and we won 3-2. It was brilliant."
No Motherwell fan can mention Pettigrew without also mentioning Graham. They were a brilliant double-act. Graham, like Pettigrew a Motherwell boy, had been signed for Liverpool by Bill Shankly and did well at Anfield before injury struck him down. He returned to Fir Park and proved a fine, bullish foil for the lithe, fox-like Pettigrew. "We had one of the most feared partnerships in Scottish football," he says. "Our previous manager, Bobby Howitt used to give team-talks, and talk the defence and midfield through their instructions. Then he'd turn to me and Bobby and say: 'And you two . . . just play up front.' That was it."
In that classic in '75, Pettigrew's opening goal, created by Graham, perfectly sums up their partnership. "Bobby and I trained together but we never really worked at anything. It was a Toshack-Keegan thing. When Bobby got the ball, I knew where to go, and he knew I'd be there. We made each other. I had pace, but Bobby was cultured, he could read the game, he could take the ball in to feet and hold it. I still see Bobby occasionally. He's living in the Motherwell area."
In his scoring heyday, however, Pettigrew's lippy style made him enemies. One of those proved to be Ally MacLeod, whose mental scarring at the 1978 World Cup with Scotland required him to seek solace six months later in that well-known sanatorium: the Motherwell manager's office. By then, Pettigrew had been capped and was on - relatively speaking - a fat salary of nearly £200-a-week at Fir Park.
MacLeod wanted him out, and Pettigrew almost moved to St Pauli in Germany the previous season. Amazingly, he also played through some of his prime years with a terrible injury. "I ruptured a muscle in my left leg. This was in that era when they said 'it's all in yer mind' or 'stamp it off'. On a Saturday, unless your leg was in two, you were expected to play. I went to see a specialist and even he said, 'ach, you'll be fine, just don't think about it on the park.' Well, after games my leg blew up to twice its normal size. I said to Willie [McLean], 'look at this, boss, I'm telling you, my leg's not right!' I was in agony after matches.
"I'd nearly signed for St Pauli the previous season [in 1977]. I flew over there with Wee Willie [McLean] and Bill Dickie. We met their officials, and they wanted me. Motherwell were looking at the money they were going to get for me and were pretty keen. I said to Bill, 'the club will get £365,000 out of this sale . . . and what will I get?' He said to me, 'what d'you mean? You'll get nothing.' I said, 'okay, let's all fly home . . . I'm not into this.' That was at the time when I had my injury, and I knew I'd fail a 'physical'. But Willie was desperate to get his hands on the money.
"When Ally MacLeod wanted me out, and Jim McLean came in for me, I thought, 'why not, there are no other offers'. So I went to Tannadice and spent two years, good and bad."
Those years - 1979 to 1981 - proved a decent second innings for Pettigrew. He scored twice against Aberdeen in the 1979 League Cup final, and was United's top scorer in his first season. But injuries, then a classic Jim McLean fall-out, put paid to it all. "It was very intense at Dundee United under Wee Jim . . . a great manager, but terrible man-management. Dreadful. United had a smashing player in midfield at the time, Graeme Payne. What a player he was. But Wee Jim used to berate him. Jim thought the best way to get the best out of someone was to slag them rotten, and Graeme just couldn't handle it.
"In the 1981 Scottish Cup final replay against Rangers, I didn't play, having been dropped. United lost 4-1 and Wee Jim came in afterwards and jabbed his finger at me and Graeme and said: 'You two cost us this final!' I said to him, 'what the f*** are you talking about, I didn't even play!' Jim, ever perverse, said, 'aye, but you should have been pushing these players much harder, to keep them on their toes.'
"He then turned to me and added: 'Go and find yourself another club.' I said to him, 'well thank f*** for that.' When I did finally get a move, and told Jim I was off to Hearts, he had the nerve to say, 'ach, Willie, I wish you'd stay here and fight for your place.' I said 'no thanks'.
Pettigrew would finish his career at Hamilton, and had a grocer's business after his playing days. He now works in Asda and coaches Motherwell's under-14s. "I loved my days as a player," he says. "In Motherwell everyone knew me and, if I scored, I made many people happy. What a time I had."