Powell: I could still play the drums, but I couldn’t remember any of the songs. On our first rehearsal back we played “Cum On Feel The Noize” and I had to ask how the song went. I remember once playing “Merry Xmas…” as an encore and I had to ask the others to sing it to me so I could remember how it went. It was very strange at the time, with the amnesia. But they didn’t treat me that different, I had to fend for myself which was better than having everything done for me.

Holder: We went to record it in America. We put it down, and we had to record it in a way we’d never recorded before. We’d always gone in the studio and played a song straight through. We’d then do a bit of overdubbing at the end, but it was essentially a live take and usually the vocals were live as well. But with “Merry Xmas…”, because of Don’s memory, he couldn’t get through a whole take, he’d forget what he was playing halfway through. So for the first time we had to record in layers, like other bands did. We put a basic take down but the only thing I think that is live from the original take is the bass drum. We then overdubbed everything bit by bit. Fuck, it took a long time! We had to get the feel of it, it wasn’t a typical Slade song, but it took shape.

Powell: We were in America and had a week free so Chas sent us into the studio and “Merry Xmas Everybody” was one of the songs. I was struggling to remember things and at the time Nod would sing vocals over a live backing track, but this time Nod had to show cues to me while he was singing so I knew what was happening. If you listen to it very closely there’s one drumbeat at the very end where I just forget to stop. You can hear it right at the end, one extra faint drumbeat.

Lea: It was the first song we ever multilayered. Normally Chas would book two weeks in the studio and we’d just go in without rehearsing and teach ourselves. But Don had his accident and was looking round bewildered, and there was something about the ragtag sound of it that was really good.

Holder: Chas loved singers and if you listen to the recording it was all about the singer. When he recorded, he built everything around the singer. A lot of producers didn’t think that way and it led to a few barneys in the studio. Chas was bombastic and ruled with a rod of iron, but he was open to suggestions and always willing to have a listen. He was music mad, he wasn’t just a money man. He’d been in a band and then managed and produced Hendrix, and we got the benefit of all that experience. He knew what he was doing and we learnt a lot from him.

Powell: We recorded it at the Record Plant in New York where Lennon was always recording. There was a heatwave outside and we were singing about Christmas – we got some strange looks on the American engineers’ faces, I can tell you.

Hill: We went out in the corridor to get the echo and give the impression of a singalong, and all these Americans were walking past in their suits thinking we were off our rockers singing about Christmas in the summer.

Holder: Lennon was in the next studio and we actually borrowed his harmonium to play the opening chords. Those first notes are on Lennon’s harmonium.

Powell: It must be the same with many artists, ’cos we finished recording it but were a bit unsure about releasing it. But Chas said I don’t care what you think, this is coming out this Christmas and it will be No 1. We thought it was a bit namby-pamby, we just weren’t sure at all. But we were proved wrong by Chas.

Holder: Chas loved it and took it back to the UK while we went on tour. He didn’t warn them but just played it in the office in front of the marketing men and they loved it, they flipped. They had no idea we were going to bring them a Christmas record and they were over the moon, cock a hoop. We’d already had “Cum On Feel The Noize” go straight to No 1 on the first day of release, same with “Skweeze Me Pleeze Me”. “My Friend Stan” was meant to be a stopgap but had done well and then we gave them this.

Hill: I wasn’t sure about it at first. It was being recorded in summer and we weren’t thinking about Christmas. So we put it to one side and then in November it suddenly sounded different. The weather was changing, it just sounded different. I was in Belgium with Jim and our wives and we had a drink with a guy from the record company and he said he thought it was terrific, he really had a feeling about it. And you’re sitting there and you could hear what he meant. I started to get a tingle down my back. It suddenly made sense. The atmosphere was gelling around it.

Holder: We knew it was going to be a hit, but we never guessed it would be as big as it was. It had a life of its own. We went straight to No 1. We sold more than 500,000 on pre-orders, on the first day of re-orders we sold another 400,000 and it went on to do a million over two weeks. It was No 1 until the end of January.

Hill: My strong memory is Chas rang me and his first words were, “Are you sitting down, man?” Then he told me how many it had sold in one day. It was phenomenal. They had to press records in Germany because they couldn’t do enough in England. You’ll never see those sorts of figures now for a single. It was just everywhere. There’s nothing more powerful than a great idea when it’s time had arrived. And we were a band with a great idea and its time had arrived.

Powell: No matter where you went, you heard it. You’d be in the supermarket paying for groceries and the girl would be singing it as you handed over the money, or you’d be in a lift and it would come on and everybody in the elevator would start humming. It’s still like that! It’s not quite a rod for our own back, I’m proud of these records, but I’m amazed it’s still being played.

Hill: Each year it gathers new momentum. I’m always being approached by kids asking for my autograph saying I’m that “Merry Xmas bloke”. We had some great songs, some amazing No 1s, but that song will always be the one people remember.

Holder: Now it’s the only song people think we ever did. It’s had a life of its own and it helps sustain the band’s product and back catalogue. It’s kept us afloat in many ways.

Lea: Talk about a pension…