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M&S

Heatgen™ Medium Thermal Long Johns

£20

Colour

Size

Free standard delivery over £60

Product code: T148814N

About this style

These thermal long johns provide medium warmth with a regular fit, perfect for cooler days as a base layer underwear. The insulating brushed-back fabric offers breathability for lasting comfort, while comfort seams ensure a snug feel. Featuring Heatgen™ technology that helps generate and retain body heat when temperatures drop, making this undergarment ideal clothing for layering. M&S Collection: easy-to-wear wardrobe staples that combine classic and contemporary styles.

Medium warmth for wrapping up in moderately cold conditions.

Details & care

Style

Regular fit

Button fastening

Features

Thermal

Soft and cosy brushed fabric that keeps warmth in

Heatgen™ technology

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

Composition

50% cotton, 26% polyester and 24% viscose (exclusive of trimmings)

Care

Wash at 40°C

Do not bleach

Tumble dry medium temperature

Iron at medium temperature

Do not dry clean

Delivery, collection & returns

Delivery

Standard

UK Standard Delivery is available for £3.99 or free on orders over £60 (excluding furniture).

Nominated Day

UK Next Day Delivery and UK Nominated Day Delivery (excluding Northern Ireland) are available for £5.99 (excluding furniture)

Collection

Collect from store

Store collection is free on all fashion, home and beauty orders.

Returns

UK returns

Free

Exclusions apply

Full delivery and collection informationOur returns policy

Reviews (578)

4.7

73% Recommended this product

Mentions
28 December 2025Drudesss
Verified Purchase

Just the job for cold weather

Yes, I recommend this

Good quality comfy and movement they wash well keeping shape

Helpful?

24 December 2025Welwyn x
Verified Purchase

Worth the investment

Yes, I recommend this

Excellent Quality , Very Comfortable and most importantly keep my Arthritic knees happy

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

21 December 2025mmpenny
Verified Purchase

Seemed Good

Yes, I recommend this

I tried but hubby's not a fan, so returned unopened

Helpful?

21 December 2025Johnkirk
Verified Purchase

Excellent Thermals

Yes, I recommend this

Really pleased with this product. Keep you warm, but not sweaty. Perfect fit. Bought a second pair I was that impressed

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

20 December 2025
Verified Purchase

Great quality, good price.

Yes, I recommend this

I will be spending Christmas in a very cold part of Europe, these items are so well made I know I will not be cold.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

19 December 2025Montyboy57
Verified Purchase

Do the job well!

Yes, I recommend this

Good quality. Soft, warm material that isn’t too thick or too heavy.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

18 December 2025Koumak
Verified Purchase

Classic

Yes, I recommend this

Good quality material, warm without being too thick. Soft and nice stretch.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

09 December 2025Mje59
Verified Purchase

Great product

No, I don't recommend this

Excellent quality and really warm. Definitely recommend

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

09 December 2025SueNana
Verified Purchase

Keep snug and warm in these

Yes, I recommend this

Very warm and perfect for the less mobile on cold winter days also helps to save on the heating bills

Helpful?

09 December 2025Glyn73
Verified Purchase

Great quality at a great price. Thanks M&S

Yes, I recommend this

Excellent quality at a good price. M&S rarely disappoints.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

05 December 2025Zilpah
Verified Purchase

Great Colour

Yes, I recommend this

Nice to find these thermal pants in a different colour, ideal as an extra layer for going to watch the football in the cold weather.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

03 December 2025Fiab
Verified Purchase

Great replacements

Yes, I recommend this

Bought for my husband, who liked the new colours and hasn’t complained about them, so presume he is happy.

Reviewer Ratings

Comfort

Good

Helpful?

Reviewer Ratings

Comfort

Good

30 November 2025Drew65
Verified Purchase

Drews

Yes, I recommend this

Good quality item and good value for the money 👌 .

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

29 November 2025L p Loy
Verified Purchase

Great Value

Yes, I recommend this

Excellent value product. Great fit and ordering process (in store collection) was super fast .

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

21 November 2025Ray244
Verified Purchase

Don't bother

No, I don't recommend this

No real warmth felt even under additional clothes.

Reviewer Ratings

Comfort

Average

Helpful?

Reviewer Ratings

Comfort

Average

16 November 2025MikeTL
Verified Purchase

Brilliant product

Yes, I recommend this

As an arthritis sufferer the warmth from these thermals is so good and helpful

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

16 November 2025LGJG
Verified Purchase

Good quality.

Yes, I recommend this

Good quality, nice fit. Very soft fabric and comfortable round waist.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

16 November 2025Frinqui
Verified Purchase

Nice and warm

Yes, I recommend this

Nice and warm for under trousers when working outside

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

12 November 2025CHEPI1
Verified Purchase

Warm Soft and very cosy

Yes, I recommend this

Perfect to keep warm when the weather gets colder.

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

12 November 2025ILoveClothesandShoes
Verified Purchase

Great and long-lasting quality.

Yes, I recommend this

I have been buying Heatgen clothes from M%S for a longtime. I find them so warm, cozy and comfortable. They are wonderful to use in the winter months at home or when out. It saves using the heating all day. They are so good, I now have my husband buying them! I recommend them to anyone. Can you please provide more colours?

Reviewer Ratings

Comfort

Excellent

Helpful?

Reviewer Ratings

Comfort

Excellent

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