Maximum pension contribution

As a contractor with a limited company, my limited company is allowed to contribute up to £40k per year to a company pension plan tax free. I believe there is also a provision for a catchup period of three years. I.e., if I made no contributions in the previous two years, in year 3 I would be able to contribute £120k tax free.

In the US / UK tax treaty, Article 18 section 5 b states:

(b) The reliefs available under this paragraph shall not exceed the
reliefs that would be allowed by the United States to its residents for
contributions to, or benefits accrued under, a generally corresponding pension
scheme established in the United States.

Based on this treaty, can I still contribute £40k / year tax free, or would the maximum be lower due to a US cap on contributions?

Thanks.

I think the key here is what would be a "corresponding pension"....you might want to look at the retirement plans available to small businesses and sole proprietors in the US as they have significantly higher contribution limits that the regular 401k type plans