Whilst you may refer to this period with L&G as augmentation, it is most likely going to be some sort of a secondment, where you are moved to work with a third party for a period of time. Such periods of work will usually be covered by a separate secondment agreement which would have dealt with the actual terms of this move, including what you could have expected on your return to your usual employer TCS.
In the absence of such an agreement, then you need to look at what was agreed with you or what the usual practice in such situations is. For example, if you can show that others that have been through similar situations and have always returned to their original job then that would certainly help. However, any uncertainty over this, for example where some have returned, others have not, would imply that there was no guarantee that you would return to your original job, whatever the reasons for that.
If there was an indication you would be returning to your job or can demonstrate this has always been the case then you can indeed be looking at potential constructive dismissal, which occurs when the following two elements are present:
- Serious breach of contract by the employer; and
- An acceptance of that breach by the employee, who in turn treats the contract of employment as at an end. The employee must act in response to the breach and must not delay any action too long.
A common breach by the employer occurs when they, or their employees, have broken the implied term of trust and confidence. The conduct relied on could be a single act, or a series of less serious acts over a period of time, which together could be treated as serious enough (usually culminating in the 'last straw' scenario).
The affected employee would initially be expected to raise a formal grievance in order to officially bring their concerns to the employer's attention and give them an opportunity to try and resolve them. If the issues are so bad that the employee can't even face raising a grievance, or if a grievance has been raised but has been unsuccessful, then they can consider resigning straight away.
If resignation appears to be the only option, it must be done without undue delay so as not to give an impression that the employer's breach has been accepted. Any resignation would normally be with immediate effect and without providing any notice period. It is advisable to resign in writing, stating the reasons for the resignation and that this is being treated as constructive dismissal.
Following the resignation, the option of pursuing a claim for constructive dismissal exists. This is only available to employees who have at least 2 years' continuous service. There is a time limit of 3 months less a day from the date of resignation to submit a claim in the employment tribunal.
As an alternative to resigning or claiming, the employer may be approached on a without prejudice basis (i.e. off the record) to try and discuss the possibility of leaving under a settlement agreement. Under a settlement agreement, the employee gets compensated for leaving the company and in return promises not to make any claims against the employer in the future. It is essentially a clean break, although the employer does not have to agree to it so it will be subject to negotiation.
Just to make a final, yet important point, constructive dismissal can be a difficult claim to win as the burden of proof is entirely on the employee. Therefore, constructive dismissal should only be used as a last resort and all else fails.