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Comparing these with the results of the recent studies for the two individual parameters [21, 27] we see only a mild changes in the best fit and confidence intervals for α , while the changes are somewhat larger for G . 

More importantly, a degeneracy is clearly present be- tween λ$_{G}$ and the fine structure constant. The underly- ing reason is easy to understand. A change in α shifts the recombination epoch, affecting the angular diameter distance at recombination and the peaks position in the CMB anisotropy angular spectra. A similar effect can be obtained by changing the value of λ$_{G}$ and the two pa- rameters are therefore degenerate. Both parameters are degenerate with the Hubble constant H 0 as we can see from Figures 2 and 3. 

From the above it follows that including the recent HST measurements of H 0 has an important effect: it breaks the α - H 0 and λ$_{G}$ - H 0 degeneracies and thereby provides a stronger bound on those parameters. This is clearly shown in the third row of Table 1. 

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As already mentioned in the introduction, from the perspective of mode-building it is interesting to consider 

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the behavior of the Q parameter, which in terms of our analysis pipeline is defined as 

Obviously, since the current data doesn’t show any ev- idence for variations in G or α it is not possible to rule out any of the models discussed before. The CMB data, however, does show a clear correlation between α and λ$_{G}$ that could be fitted with a linear relation. Considering the models that are inside the 95% confidence level we found constraints on the best-fit Q parameter as reported in Table II. 

The data therefore prefers a value of Q whose value is significantly larger than zero, and again we see that the HST prior has a very strong effect. Taken at face value, this result would therefore strongly disfavor the models we mentioned in the introduction as having Q negative for λ$_{G}$ ∼ 0 . 1 in absolute value. In other words, if there are any variations at or around the percent level, then the variations of the two parameters must have the same 

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