- Companies
- Plumbers and heating engineers
- London
- Williams Mechanical Ltd
Williams Mechanical Ltd
- Company number
- 10385737
- Incorporated
- 20 Sep 201610 years trading
- Registered office
- 167-169 Great Portland Street, 5TH Floor, London, W1W 5PF
- Nature of business
- Plumbing, heat and air-conditioning installation
Williams Mechanical Ltd is a 10-year-old private limited company registered in London, company number 10385737, one of 2,972 plumbing and heating companies in London. Its next accounts are due at Companies House on 29 June 2027, and the CT600 for the period to 29 September 2026 is due at HMRC on 29 September 2027.
Key dates
Worked out from the year end and filing history on the Companies House register.
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Finances
From each year's balance sheet filed at Companies House. Small companies do not have to publish turnover or profit, so these are balance sheet figures.
- Net assets down £1,445 (-1.3%) on the year before, to £110K.
- Net assets rose in 5 of 8 year-on-year comparisons on record.
- Current assets of £140K against £37K owed within a year: 3.8 times cover.
- 1 employee on average during the year.
- Balance sheets on record for 9 years, 2017 to 2025.
Net assets by year
| Year end | Net assets | Cash | Current assets | Owed within a year | Employees |
|---|---|---|---|---|---|
| 29 Sep 2025 | £110K | £140K | £37K | 1 | |
| 29 Sep 2024 | £112K | £135K | £22K | 1 | |
| 29 Sep 2023 | £137K | £202K | £56K | 1 | |
| 29 Sep 2022 | £117K | £197K | £64K | 1 | |
| 29 Sep 2021 | £156K | £260K | £75K | 1 | |
| 30 Sep 2020 | £147K | £32K | £220K | £51K | 1 |
| 30 Sep 2019 | £109K | £2,805 | £140K | £32K | |
| 30 Sep 2018 | £17K | £1,789 | £24K | £8,057 | |
| 30 Sep 2017 | £4,041 | £1,979 | £5,217 | £2,338 | 2 |
Where Williams Mechanical Ltd is registered
The registered office is in London (W1W), in the Westminster local authority area, London. Show W1W 5PF on a map.
Other trade companies in W1W
- Civaris LtdSpecialist contractors
- R&R Construction Group LtdBuilders
- Aurum Cooling LtdPlumbers and heating engineers
- Steam Wood Stone LtdFinishing trades
- Hau Developments LimitedProperty developers
- Group Atlas Financial 83 LtdPainters and decorators
- Energy Reward LtdMotor traders
- Holly’S Housekeeping LtdCleaning companies
Shared registered office
1,494 companies on our pages use this registered office address. An address shared this widely is usually an accountant's office or a company formation agent's service address, not where the business trades from.
What happens if Williams Mechanical Ltd files late
Companies House charges an automatic penalty the day after the deadline, and it rises the longer the accounts are late. These are the dates for this company's accounts due on 29 June 2027.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 30 Jun 2027 to 29 Jul 2027 | £150 |
| 1 to 3 months late | 30 Jul 2027 to 29 Sep 2027 | £375 |
| 3 to 6 months late | 30 Sep 2027 to 29 Dec 2027 | £750 |
| More than 6 months late | From 30 Dec 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 30 Sep 2027 | £200 |
| 3 months late | 29 Dec 2027 | another £200 |
| 6 months late | 29 Mar 2028 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 29 Sep 2028 | another 10% of any unpaid tax |
For returns filed on or after 1 April 2026. Late three times in a row and the £200 penalties become £1,000 each.
Company details
As held on the Companies House register.
- Company number
- 10385737
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 20 September 2016 (10 years ago)
- Registered office
- 167-169 Great Portland Street, 5TH Floor, London, W1W 5PF
- Nature of business
- Plumbing, heat and air-conditioning installation (SIC 43220)
- Year end
- 29 September (accounting reference date)
- Accounts type
- Micro-entity
- Last accounts made up to
- 29 September 2025
- Last confirmation statement
- 12 December 2025
- Previous names
- One Four Plumbing Limited (until 29 Apr 2019)
NZ14 Limited (until 19 Jul 2018)
Filing notes for plumbing and heating companies
Plumbing and heating companies frequently work under CIS for main contractors and also directly for homeowners, so turnover can mix CIS and non-CIS income.
Similar companies in London
Other active plumbing and heating companies registered in London.
- Wilz & Co. Ltd2022
- Wimbledon Aircon Limited2020
- Wimbledon Plumbers Limited2016
- Winter Feeling Ltd2025
- Wizz 24/7 Property Maintenance Ltd2024
- WMS Plumbing and Heating Ltd2017
- WN Plumbing Ltd.2019
- Wo Solutions Limited2025
All plumbing and heating companies in London · All trades in London · Plumbers and heating engineers across the UK
Frequently asked questions
When are Williams Mechanical Ltd's accounts due?
Williams Mechanical Ltd's next accounts are due at Companies House by 29 June 2027 (in 259 days), covering the period to 29 September 2026.
When is Williams Mechanical Ltd's CT600 due?
The CT600 for the period to 29 September 2026 is due at HMRC by 29 September 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 30 June 2027.
Is Williams Mechanical Ltd still trading?
Williams Mechanical Ltd is listed as active on the Companies House register as of 1 Oct 2026. Active means it has not been dissolved or entered insolvency; it does not show whether it is currently taking on work.
What does Williams Mechanical Ltd do?
Williams Mechanical Ltd is registered under Plumbing, heat and air-conditioning installation (SIC 43220).
How old is Williams Mechanical Ltd?
Williams Mechanical Ltd was incorporated on 20 September 2016, 10 years ago.
What is the penalty if Williams Mechanical Ltd files its accounts late?
Companies House charges £150 if the accounts are up to 1 month late, £375 up to 3 months, £750 up to 6 months and £1,500 after that, doubled if the previous year's accounts were also late. HMRC charges £200 for a CT600 filed a day late and another £200 at 3 months.
Official records
View Williams Mechanical Ltd on Companies House for filed documents, officers and the full history.
Based on the Companies House register (snapshot 1 Oct 2026). Deadlines are worked out from the register and assume a standard accounting period; a change of year end or a short period moves them. This page is general information, not tax or accountancy advice.