We present results derived from VLT–FORS2 spectra of 24 different globular clusters associated with the lenticular galaxy NGC 3115 .
A subsample of 17 globular clusters have sufficiently high signal–to–noise to allow precision measurements of absorption line-strengths .
Comparing these indices to new stellar population models by Thomas et al .
we determine ages , metallicities and element abundance ratios .
For the first time these stellar population models explicitly take abundance ratio biases in the Lick/IDS stellar library into account .
Our data are also compared with the Lick/IDS observations of Milky Way and M 31 globular clusters .
Unpublished higher order Balmer lines ( H \gamma _ { A,F } and H \delta _ { A,F } ) from the Lick/IDS observations are given in the Appendix .

Our best age estimates show that the observed clusters which sample the bimodal colour distribution of NGC 3115 are coeval within our observational errors ( 2–3 Gyr ) .
Our best calibrated age/metallicity diagnostic diagram ( H \beta vs [ MgFe ] ) indicates an absolute age of 11–12 Gyr consistent with the luminosity weighted age for the central part of NGC 3115 .
We confirm with our accurate line-strength measurements that the ( V - I ) colour is a good metallicity indicator within the probed metallicity range ( -1.5 < \mathrm { [ Fe / H ] } < 0.0 ) .
The abundance ratios for globular clusters in NGC 3115 give an inhomogeneous picture .
We find a range from solar to super-solar ratios for both blue and red clusters .
This is similar to the data for M 31 while the Milky Way seems to harbour clusters which are mainly consistent with [ \alpha / \mathrm { Fe } ] \simeq 0.3 .
From our accurate recession velocities we detect , independent of metallicity , clear rotation in the sample of globular clusters .

In order to explain the metallicity and abundance ratio pattern , particularly the range in abundance ratios for the metal rich globular clusters in NGC 3115 , we favour a formation picture with more than two distinct formation episodes .