Outsourced SDR Services for London based Companies

An SDR Agency that London Companies That Can't Wait
to Hire

Building an in-house SDR team takes 6 months and costs £85k a year per rep. Whistle gives you a fully managed SDR function in 10 business days with the people, tech, data, and playbook to start booking qualified meetings this month.

Over 350+ Companies Trust Whistle
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Hiring SDRs in London is broken.

By the time your first in-house SDR is hitting quota, the market has moved on. Whistle gives you a tested, managed, multi-skilled SDR function without the recruiting, the churn, or the £85k all-in cost per head.

£45k+

Median London SDR base salary, before commission or benefits

18+ months

Average SDR tenure in UK SaaS. Then you're back to recruiting.

6+ months

Typical time to recruit, onboard, and ramp a single SDR

From kickoff call to live outreach in 10 days.

No lengthy onboarding. No tech integration on your side. Just a calendar link and a clear ICP.
Step 1
Discovery
We deep dive into your current setup, lead sources, ICP, average deal size and current conversion rates in order to understand how to best achieve your revenue goals.
Step 2
Strategy
Based on the above we build a tailored outreach strategy in order to achieve the best results in the fastest time. Prioritizing your lead sources, segmenting your ICP, and selecting the best outreach channels.
Step 3
Onboarding
Our 10 day onboarding process is designed to be fast yet thorough - we'll set up the outreach systems, build the target data lists, create the messaging, place the best suited SDR's and ensure the team is ready to launch.
Step 4
Execution
With our proven systems and strategy in place, your outsourced SDR team starts outreach to your ICP and fills your sales team's calendars with qualified leads.
Step 5
Review
We believe in full transparency - you'll receive daily, weekly, monthly and quarterly reports on output activities and results. You'll also meet with your customer success manager weekly to strategize and review.
Step 6
Improve
Based on our years of experience, quantitative and qualitative reporting insights, and weekly strategy sessions with you, we'll double down on what's bringing in revenue, and stop what isn't.
Why London companies choose Whistle

Not just another SDR agency.

01

Live in 10 business days

Most SDR agencies onboard in 4–6 weeks. We get you live in 10 days. From kickoff call to first outreach, faster than you can finish interviewing candidates.

02

0.2% SDR acceptance rate

We hire 1 in 500 SDR applicants. Your reps are not generalists, they're top performers who've been through our rigorous selection process.

03

No Tech Integration Needed

We bring our own stack - dialler, sequencer, data. You just need a calendar link. Nothing to install, configure, or maintain.

04

Multi-channel by default

Phone, email, and LinkedIn, coordinated, not siloed. Single-channel SDRs leave 60% of pipeline on the table. We don't.

05

Customer Success Manager

An experienced and dedicated customer success manager ensures your campaign strategies are in place, your team stays focused, and that we achieve our results.

06

Reports and Insights

You'll have access to live reporting including insights into campaign performance by geography, titles, industry, company size and other metrics.

In-house vs Whistle

The comparison most agencies
won't show you.

We did the maths honestly. Here's what each option actually costs, in time, money, and risk.
Whistle — Comparison Table
Internal SDR Hiring in-house
Whistle Outsourcing with Whistle
Headcount
1 person · 8 hrs/day (set hours)
2 SDRs · flexible hours + Data, Copy & Strategy teams
Average hiring time
45 days
10 days
Average ramp-up
3 months
Hits the ground running
SDR retention
6–12 months
2 years
Cost of downtime
£8,900
£0
Replacement time
3 months
5–10 days
Underperformers
1–3 months notice required
Swap out SDRs in 5 days
Commitment
14-month average career, then rehire
Month to month long-term option available
Tech stack
Licences, credits & setup on you
All included
Hiring & training
Done by you
Fully managed by us
Reporting
Done by you
Fully managed by us
Additional resources
Training, management, systems, tech & benefits
Access to tech systems | 1× bi-monthly meeting

Trusted by Growing
Revenue Teams

They Whistled. We Gave Them Pipeline. From early-stage startups to enterprises, our clients share how Whistle changed the game.
View More

They Whistled. We Delivered.

From early-stage startups to global enterprises, our clients share how Whistle changed the game.

"Whistle provided us with the structure and support we needed to make outbound a viable and repeatable part of our sales strategy. Their team was responsive, collaborative, and proactive in helping us test and learn what worked best for our audience."

Andrea Brown
VP of Marketing

“We knew the type of talent Whistle had access to, and they exceeded our expectations. Their BDR has helped us expand our pipeline and given us the bandwidth to focus on what we do best—delivering value to our clients.”

Ari Barmapov
Co-Founder & Head of Business Development

“Whistle provided an out-of-the-box solution for sales development, which was exactly what we needed to get up and running quickly. Their team’s ability to pivot strategies and maintain transparency throughout the campaign made them an invaluable partner in our business.”

Jamie Schell
Chief Business Officer
“We work very well together with Whistle. The communication is perfect. Any training or other requests I have for the Whistle team happen very quickly.”

Orel Levit
Director of Sales

Our Other Services

Whether you're refining your CRM, filling data gaps, or building a pipeline from scratch, our services are designed to meet you at your stage of growth and help you move forward faster and more efficiently.

Cold Calling

Convert leads through conversations. Our SDRs harness the phone to build trust and book qualified meetings for your sales team.
Explore This Service

Cold Email Outreach

Fill your calendar with warm meetings. We craft high-performing email campaigns, sparking real conversations that convert.
Explore This Service

LinkedIn Outreach

Build more connections with your ideal buyers. We run personalized LinkedIn outreach that earns replies and strengthens your network.
Explore This Service

Pipeline Generation

Never worry about top-of-funnel again. We build a steady stream of qualified leads so your team can focus on closing, not chasing.
Explore This Service

RevOps for HubSpot

Turn your HubSpot CRM into a revenue machine. We maintain your CRM, automate key processes, and help Sales and Marketing move faster.
Explore This Service

Data on Demand

Reach decision-makers, more easily. Our team delivers accurate, verified leads so your outbound never stalls because of bad data.
Explore This Service

Not Sure Which Service Is Right for You?

Let’s figure it out together. Book a quick call and we’ll walk you through the best-fit options based on your goals, team structure, and current setup.

Frequently Asked Questions

Where are Whistle's SDRs based?
How much does outsourced SDR cost in London?
How fast can we launch?
Do you specialise in any industry?
Are you a UK-only agency?
Do we own the meetings booked?
Can we scale up or down?
Is there a minimum contract length?

Can I trial Webflow before paying?

Sure! You can test out Webflow on our free plan where you can experiment with 2 projects. Your unhosted projects will have a two-page limit, but you can purchase a site plan on a per-project basis to unlock up to 100 static pages and additional CMS pages.

What is a project?

A project is a website that you build in Webflow. You can publish projects to a webflow.io staging subdomain for free, export the code on a paid plan, or add a site plan to connect your custom domain and unlock hosting features.

What can I white label?

Pro accounts can add their own logo to Client Billing forms and the Editor. Pro accounts can also remove references to Webflow in the source code and form submission emails, and hide the Webflow badge from their staging sites.

How much traffic can the hosting handle?

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Webflow hosting scales automatically to handle millions of concurrent visits. All site plans serve sites through our Amazon's Cloudfront CDN and accelerated using Fastly, loading sites in milliseconds.

What kind of support does Webflow provide?

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We offer fast email support to paid accounts and prioritized help for team accounts. Community support (forum.webflow.com) is available to free accounts.

How long does it take to learn Webflow?

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If you're new to building websites, our video tutorials will get up and running quickly. If you already know concepts behind CSS and the box model, you will feel at home in Webflow.