Long-term review · Updated May 2026
Mountfield SP46 Review
By The Best Mowers UK · 3 years on a 700 m² Norfolk test lawn
Specs
| Cutting width | 46 cm |
|---|---|
| Engine | Mountfield ST 140 OHV (139 cc, Italian) |
| Deck | Steel |
| Drive | Single-speed self-propelled (rear wheels) |
| Cut heights | 5 positions, 25–80 mm |
| Grass box | 55 litres |
| Mulching | Yes (plug included) |
| Side discharge | Yes |
| Weight | 27 kg |
| Tank | 1.0 L (E10 unleaded) |
What we loved
- The engine — three years in, ours starts on the second pull from cold every time. Italian-built ST 140 is a known-good unit and parts are everywhere.
- The price — at £329 there is genuinely nothing else combining 46 cm steel deck, self-propelled drive, and a reliable engine.
- Built-in mulching plug — comes in the box, not as an extra. Saves emptying the box during a quick mow.
- 55 L grass box — class-leading capacity. We empty it once on our 700 m² test lawn.
What we didn\'t love
- Single-speed drive — the rear-wheel drive engages at one fixed pace. Fine for most users but lawns with corners benefit from variable-speed (Honda HRX or higher-spec Mountfield SP56).
- Engine warranty is shorter than Honda — 2 years vs Honda\'s 5. Reflects the price gap.
- Heavier than cordless — at 27 kg you feel it lifting over a kerb. Not a problem on its wheels, but worth knowing.
- Petrol service routine — annual oil change, spark plug, air filter. Around £25 in DIY parts or £60–£100 at a dealer.
How it compares
Closest rival is the Cobra MX46SPB at £449 — Briggs & Stratton engine, slightly more refined, £120 more. The premium alternative is the Honda HRX 476 VK at £999 — properly bulletproof, 20-year working life, three times the price. For value, the SP46 wins.
Who should buy it
Owners of medium-to-large UK lawns (500–1,000 m²) who want reliable petrol power without spending £600+. People moving up from a small electric or cordless mower. Buyers who value Italian-built engineering with UK dealer support over Japanese premium brands.
Don\'t buy it if your lawn is under 400 m² (cordless is now the rational choice), over 1,500 m² (look at ride-on), or if you specifically need variable-speed drive (look at SP56 or Honda HRX).
What real owners say
Mountfield petrol mowers generate strong opinions on r/GardeningUK — both loyal fans and vocal critics. Here\'s what real owners say, unfiltered.
"Definitely the Mountfield SP46. It is a good enough honda engine. They were a decent mid range brand but have been dropping quality wise, but still ok. Servicing and repairs are usually easy enough and parts available."
— u/Lunar-Mint, r/GardeningUK
"I have had the equivalent of the Mountfield (but older) for around 10 years. It has suffered much abuse due to the grass that we inherited when we moved here which was in terrible condition. It has kept going and going and has always been reliable."
— u/Disastrous_Proof1247, r/GardeningUK
"Mountfield has the more established name, parts probably easier to get. If you have under 200m² of grass I\'d seriously consider battery once you factor in fuel costs and servicing."
— u/UsefulAd8513, r/GardeningUK
"I\'ve got a Mountfield and am not happy with it. It only runs on the freshest of fuel so no jerrycan sat in the garden for months."
— u/Careful_Adeptness799, r/GardeningUK
The honest Reddit picture: long-term owners (5–10 years) consistently praise reliability and parts availability. The recurring complaint is fuel sensitivity — modern small engines across all brands struggle with stale E10 petrol. Our advice: use fuel stabiliser or buy alkylate fuel (Aspen 4T, about £12/L) if the mower sits unused for more than a month.