| ATLASS MOTORS LTD | Mitcham | A rating |
| Atlassian (UK) Operations Limited | London | A rating |
| ATM Automation Limited | Leicester | A rating |
| ATM VENTURES PVT LTD | Pembury | A rating |
| Atmaca Furniture Ltd | London | A rating |
| Atman Care Ltd | Dartford | A rating |
| Atmiya Enterprise Ltd | Clifton | A rating |
| Atmiya Retail Limited | Salisbury | A rating |
| Atmo Technology Ltd | Bristol | A rating |
| ATMOS INTERNATIONAL | Manchester | A rating |
| ATMOS International Ltd | Manchester | A rating |
| Atmos Lab Limited | London | A rating |
| ATMOSAIR LIMITED | New Malden | A rating |
| Atmoso Limited | Fareham | A rating |
| ATN (UK) LTD | London | A rating |
| ATN Partnership Limited | Gravesend | A rating |
| Atnahs Pharma UK Ltd T/A Pharmanovia | Basildon | A rating |
| ATNY LTD | OLDBURY | A rating |
| Atogarden Ltd T/A Kiji | London | A rating |
| Atolia & Atolia Limited | London | A rating |
| Atolls London Limited | London | A rating |
| ATOM CONSULTING SERVICES LIMITED | London | A rating |
| Atom Investors UK Ltd | London | A rating |
| Atom Learning | London | A rating |
| Atom Property Aid Ltd | Farnborough | A rating |
| Atom Scientific Ltd | Hyde | A rating |
| Atom Supplies Limited | Tonbridge | A rating |
| Atombit Limited | London | A rating |
| Atomic Arts Limited | London | A rating |
| Atomic Digital Marketing Ltd | Cheshire | A rating |
| ATOMIC FIELD LTD | London | A rating |
| Atomic Sleep Ltd | Batley | A rating |
| Atomic Wire Technology Limited | London | A rating |
| Atomico (UK) Partners LLP | London | A rating |
| Atominvest Software Ltd | London | A rating |
| Atomix Educational Trust | Guisborough | A rating |
| Atomos Investments Limited | London | A rating |
| Atomy Distribution Limited | Guildford | A rating |
| Aton Immigration Ltd | London | A rating |
| Atos Executive Limited | London | A rating |
| Atos IT Services UK Ltd | London | A rating |
| Atout France | London | A rating |
| ATOZ DISTRIBUTION LTD | Blackburn | A rating |
| ATOZ Drinks Limited | Cardiff | A rating |
| ATOZ Everthing Limited | Ashton-Under-Lyne | A rating |
| ATOZ SERVICED APARTMENTS LTD t/a home.ly | London | A rating |
| Atoz Services UK Ltd | London | A rating |
| ATOZUK LTD | NEW MALDEN | A rating |
| ATP Automotive Transmission Remanufacturing Specialists Ltd | Cannock | A rating |
| Atp Consultancy Ltd | West Sussex | A rating |
| ATP Tour, Inc. | London | A rating |
| ATPAC Limited | Harthill | A rating |
| ATPI Ltd | Wythenshawe | A rating |
| ATPUTHAM MSV LTD | Stoke-On-Trent | A rating |
| Atq Casuals Limited | London | A rating |
| ATRA LTD | SUTTON | A rating |
| Atradius | Cardiff | A rating |
| Atrato Group Ltd | London | A rating |
| Atreen Limited | Manchester | A rating |
| Atria Accountants Ltd | Bury | A rating |
| Atricure UK Limited | Bristol | A rating |
| ATRIUM CLOTHING LTD. | London | A rating |
| Atrium Consulting Ltd | Virgina Water | A rating |
| ATRIUM EVENTS LLP | Purley | A rating |
| Atrium Ltd | London | A rating |
| Atrium Underwriters Ltd | London | A rating |
| Atrium Workforce Solutions UK Ltd | London | A rating |
| ATS ACCOUNTANTS LTD | Oldham | A rating |
| ATS All Trade Solutions Limited | Newry | A rating |
| ATS Applied Tech Systems Ltd | Nuneaton | A rating |
| ATS Atlas Travel Solutions Scotland and Ireland Limited | Edinburgh | A rating |
| ATS BRISTOL LIMITED T/A GARAM MASALA | Bristol | A rating |
| ATS Carpets & Furniture world | Edgware | A rating |
| ATS Euromaster Limited | Aston | A rating |
| ATS Global Entertainment Ltd | London | A rating |
| ATS GROUP LTD T/A ALLIANCE TRANSFER SERVICE | DONCASTER | A rating |
| ATS MEDICS LIMITED | ROMFORD | A rating |
| ATS VENTURES LTD T/A Langwood Hotel | Blackpool | A rating |
| Atsaal Limited t/a Shell | Hellaby | A rating |
| ATSC TYRES & SERVICE CENTRE LTD | Ardwick | A rating |
| Atsuko Kudo Ltd. | London | A rating |
| ATSUMI & SAKAI EUROPE LIMITED | London | A rating |
| Attache London Limited | London | A rating |
| Attachment London Limited | London | A rating |
| Attactic Limited | Basingstoke | A rating |
| Attain Health Management Services Ltd | Buckinghamshire | A rating |
| ATTAR TECHNOLOGIES LIMITED | HAYES | A rating |
| Attaul Haee Manan Limited | Morden | A rating |
| Attenborough Cricket Club | Nottingham | A rating |
| ATTENBOROUGH DENTAL LABORATORIES LTD | NOTTINGHAM | A rating |
| Attend | London | A rating |
| Attend IT Limited | Brentford | A rating |
| Attensi Ltd | London | A rating |
| Attentive Carers Ltd | Macclesfield | A rating |
| ATTENTIVE FIRE LIMITED | LONDON | A rating |
| Attentive Housing Ltd | Birmingham | A rating |
| Attentive Mobile UK Ltd | London | A rating |
| Attest Technologies Limited | London | A rating |
| Attestor Limited | London | A rating |
| Attewell Limited | Middlesex, | A rating |
| Attica Exploration Limited | London | A rating |
| Atticus Partners | London | A rating |
| Attila Kaszoni | Godalming | A rating |
| Attio Limited | London | A rating |
| ATTIS ZEUS LTD | Oxford | A rating |
| ATTLEBOROUGH CONVENIENCE STORE LTD | ATTLEBOROUGH | A rating |
| Attleborough Surgeries | Attleborough | A rating |
| ATTM UK Limited TA Nisa Extra | Chigwell | A rating |
| Attock Community Sports and Cricket Club | Birmingham | A rating |
| AttoLife Ltd | Norwich | A rating |
| ATTR Group Limited T/A Mayura | London | A rating |
| Attraction Tickets Direct T/A Attraction Tickets Ltd | London | A rating |
| Attraction Tickets Ltd | London | A rating |
| Attune Acoustics Limited | Southampton | A rating |
| attune UK Limited | London | A rating |
| Attwood Academies | Cranbrook | A rating |
| Atul Narharidas Patel | Sevenoaks | A rating |
| Atul UK Limited | Cheadle | A rating |
| ATV Global Limited | Witney | A rating |
| atVenu UK LTD | Manchester | A rating |
| ATVT LTD | HARLINGTON | A rating |
| Atwal (Midlands) Limited | STOURBRIDGE | A rating |
| Atyeti Limited | London | A rating |
| Atypic Skincare Ltd | LONDON | A rating |
| ATZ MEDICAL LTD | Peterborough | A rating |
| AU & AU Holdings Ltd | Hayes | A rating |
| Au Automation Ltd | Lesmahagow | A rating |
| AU BULLIONâ??S LTD | Oldham | A rating |
| Au Depart Limited | London | A rating |
| AU MINT LTD | LONDON | A rating |
| AU Vodka Limited | Swansea | A rating |
| Au2mate Ltd | NEWPORT | A rating |
| AUA PARTNERS LTD | Glasgow | A rating |
| Aubay UK Limited | Stow-cum-Quy | A rating |
| Auberge EMEA Ltd | London | A rating |
| AUBERGINE WITH FLOWER LTD | London | A rating |
| Aubi Fashions Ltd | MANCHESTER | A rating |
| Aubrey Capital Management Limited | Edinburgh | A rating |
| Aubury and Associates Limited | London | A rating |
| Auchleach Farm | Stranraer | A rating |
| Auchrannie Leisure Limited | Brodick | A rating |
| AUCKLAND DISCOUNT STORE | Hebburn | A rating |
| Auckland Medical Group | Bishop Auckland | A rating |
| Auckland Youth and Community Centre Ltd | Bishop Auckland | A rating |
| Aucklands Care | Bournemouth | A rating |
| Auctane, Limited | London | A rating |
| Auction Eats Ltd | Preston | A rating |
| Auction House Services Limited | Eastbourne | A rating |
| AUCTION PRICE INDUSTRIAL LTD | Manchester | A rating |
| Auctionz LTD | Bradford | A rating |
| Auctree UK Limited | London | A rating |
| Auctus Accountants Ltd | North Harrow | A rating |
| Auctusio LTD | London | A rating |
| AUDACC CONSULTANCY LTD | CHEADLE | A rating |
| Audacious Church | Salford | A rating |
| AUDACIOUS SERVICES LIMITED | London | A rating |
| Audax Management Company (UK) Limited | London | A rating |
| Audemars Piguet (UK) Limited | London | A rating |
| AUDENFIELD LIMITED T/A PECKHAM POST OFFICE | LONDON | A rating |
| Audere International Limited | London | A rating |
| Audet Magna Limited | Newbury | A rating |
| Audi VW Specialist Centre Ltd | Harrow | A rating |
| Audience Collective Limited | Leeds | A rating |
| AudienceQ | London | A rating |
| Audiense Ltd | London | A rating |
| Audinate Ltd | Cambridge | A rating |
| Audio Inventions Ltd | Brighton | A rating |
| Audio Limited | Watford | A rating |
| Audio Logic Limited | Harlow | A rating |
| Audio Network Limited | London | A rating |
| Audio Partnership Plc | London | A rating |
| AUDIO SPHERE LIMITED | Mitcham | A rating |
| AUDIO VENUE LIMITED | MAIDENHEAD | A rating |
| Audio Vision Integration Ltd | Surrey | A rating |
| Audiological Science Limited | London | A rating |
| AudioMob | London | A rating |
| Audioscenic Limited | Southampton | A rating |
| AUDIOSTRIP LTD | London, | A rating |
| Audit Scotland | Edinburgh | A rating |
| Auditax | Edgware | A rating |
| Auditcare Mon Choisy Limited | Oxford | A rating |
| Auditel Rental and Service Limited | High Wycombe | A rating |
| Audlem Medical Practice | Cheshire | A rating |
| Audley Chippy Ltd | Blackburn | A rating |
| Audley Construction Services Ltd | Harrow | A rating |
| Audley Court Estates Limited | Killinghall | A rating |
| Audley Court Limited | Egham | A rating |
| Audley Cricket Club | Stoke-on-Trent | A rating |
| Audley Late Night Pharmacy Limited | Blackburn | A rating |
| Audley Mills Ltd | Essex | A rating |
| Audley Mills Surgery | Rayleigh | A rating |
| Audley Property Management Company Limited | London | A rating |
| AUDRIE LTD | London | A rating |
| Audtax Accountants & Tax Consultants Limited | London | A rating |
| AUFGABE LIMITED | Northampton | A rating |
| AUFI Limited | London | A rating |
| Aug London Limited | London | A rating |
| AUG Services Ltd | London | A rating |
| AUGER TORQUE EUROPE LIMITED | CHELTENHAM | A rating |
| AUGHTON CONVENIENCE STORE | SHEFFIELD | A rating |