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2 Pack Heatgen™ Light Thermal Long Johns

Product code: T149483

About this style

For cold-weather comfort, these lightweight thermal underwear long johns provide warmth without bulk. Cut to a regular fit for easy movement, with soft seams for comfort. Heatsealed care labels ensure all-day comfort. Heatgen™ technology helps your body stay warm by generating and retaining heat. A practical fly front fastening completes this functional layering item. M&S Collection: Easy-to-wear wardrobe staples that combine classic and contemporary styles.

Light warmth for cooler conditions and everyday comfort.

Details & care

Style

Regular fit

Fly front fastening

Added stretch

Features

Heatgen™ technology

lightweight and supersoft, designed to keep you warm when the weather gets chilly

Composition

38% acrylic, 29% cotton, 29% viscose and 4% elastane lycra® (exclusive of trimmings), Ribbing - 39% acrylic, 30% cotton, 29% viscose and 2% elastane

Care

Wash at 40°C

Do not bleach

Tumble dry low temperature

Iron at medium temperature

Do not dry clean

M&S

2 Pack Heatgen™ Light Thermal Long Johns

€36

Colour

Size

Also available in: Long Sleeve and Short Sleeve
Free standard delivery over €75

Reviews (601)

4.6

67% Recommended this product

Mentions
02 June 2026Matthew8888

Shonky Sizing

Originally posted on marksandspencer.com (UK)

No, I don't recommend this

The size is supposed to be a medium but it’s definitely a large. And it’s underwear so it cannot be returned/exchanged.

Reviewer Ratings

Comfort

Fair

Helpful?

Reviewer Ratings

Comfort

Fair

01 June 2026Maryn47

Good for extra layer

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Husband who has Alzheimers feels the cold and these give an extra layer. However I do hope they last a bit better than previous ones which kept parting from the waist band

Reviewer Ratings

Comfort

Good

Helpful?

Reviewer Ratings

Comfort

Good

01 June 2026Avo67

Good value

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Bought as replacement for my 90 yr old dad who likes his thermal underwear all year round. Always wash well and perfect fit for him

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

21 April 2026Sissy55

Good fit!

Originally posted on marksandspencer.com (UK)

Bought for my husband, who is happy with the fit. Unable to test them until later in the year when we go skiing.

Helpful?

07 April 2026Rob Highgate

Hurrah - no button!

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Fly front, so no annoying miniature button. And a good leg length too. Pleased!

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

29 March 2026AngieDC

Lightweight and soft

Originally posted on marksandspencer.com (UK)

My hubby loves these. Light enough to wear indoors, good fit and wash well

Helpful?

16 March 2026dwarfie

Great quality and good value.

Originally posted on marksandspencer.com (UK)

Bought these for my husband to wear under walking trousers. He is delighted with them and pleasantly surprised at the quality as they were inexpensive.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

12 March 2026Jo JH

Comfortable

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Very comfortable, slightly big but kept me warm, prefer the men’s as they come up to my waist

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

11 March 2026Trampus94

Toasty warm

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Excellent base layers, kept me nice and warm when outside in the evening on the petanque terrain.

Helpful?

08 March 2026Happy Eva After

Fantastic quality

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

My husband LOVES these! Lightweight but warm, wash really well and dry without bobbling.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

05 March 2026Jim697

Good quality

Originally posted on marksandspencer.com (UK)

Just what I’m needed to keep me warm. Good colour and texture

Reviewer Ratings

Comfort

Good

Helpful?

Reviewer Ratings

Comfort

Good

06 February 2026lisa9003

Very warm and comfortable

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Great product ... kept us warm in -18 and not too think to wear under jeans

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

04 February 2026WorkingMum1000

good quality and price

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Bought these for my husband-add warmth with out bulk at a good price

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

31 January 2026Nickyj1

Great quality

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Perfect fit great breathable fabric nice and soft with a good stretch

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

30 January 2026KimFH

Good quality and comfortable

Originally posted on marksandspencer.com (UK)

The product is good quality and comfortable providing warmth in the Scottish winter!

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

29 January 2026standsoutside

Good quality and value

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

My husband likes this thermal underwear. He prefers them to the heavier weight ones as they are a closer fit and keep him warm. I think they must be quite stretchy as he is a 40” waist and the Medium fit well. They also wash well and dry quickly.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

27 January 2026mikkim

Excellent product

Originally posted on marksandspencer.com (UK)

My husband finds that the long john's are perfect for the cold weather . They keep him nice and warm .

Helpful?

26 January 2026AshleyP

Comfortable and warm

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Silky, soft material with enough stretch to adjust easily for movement and provide warmth for those with cold legs. Does not ride up like shorter pants, even when sat on soft furnishings. Gusset is convenient yet secure. Ideal winter wear indoors or out.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

24 January 2026Billy555

Great quality, good price

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

I have purchased these before. These performed great so I came back for more.

Helpful?

22 January 2026Ajwb

Keeping warm

Originally posted on marksandspencer.com (UK)

Yes, I recommend this

Bought these for my husband as he spends a lot of time outdoors he loves them keeps him very warm

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

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